you can corrected this type of model by using software like Meshmixer (free) and the function - Make Solid -

or - Shrink Wrap - in more professional software like Materialise Magics.

This is in no ways a slicer software problem..

the title of this thread simply states the fact that even after several years and updated versions these issues/bugs still exist in each version as if they never found them. each new version dumbs down the process yet they dont truly address issues less knowledgeable users face nor do they keep features experienced users like. so why change anything if nobody gets improvements wanted? even competitors do this to the point we are limited by what the app can or cant do sufficiently for all printers.

There's old adage among programmers that says that the day a program is bug free, it's the day it's obsolete.  There's no such thing as a bug free program, and complex programs such as Slic3r or Cura do an excellent job of making printable code out of "questionable" models.

The problem you have has nothing to do with Slic3r or Cura or NetFabb.  The problem is with the model.  Not because it's "defective", but because it's not printable.  The reason it's not printable is because it was most likely designed to be printed at a larger scale.

You are getting yourself very frustrated trying to print very small models, using a printing technology that's simply not meant for that type of work.  Then you download models with fine details, scale them down, and expect them to print, and when they don't you get frustrated and blame everything, except ... your common sense.

I would expect that by now you're aware of the capabilities of your printer.  So it should come to no surprise that some of these models will simply fail when scaled down to such small sizes, that your printer cannot resolve their features.

NetFabb did not find any problems because there were technically no problems.  It has no way of knowing what you plan to do with the model, it has no idea you're trying to print it at a scale the printer is not capable of printing, so as far as Netfabb is concerned, the model was fine.

The you brought it into RH, and sliced it with Slic3r.  I don't know what your settings are, or what your printer setup is like, but Slic3r did the best it could.  It even ignored the minimum line width (0.42 or 0.48mm), and created a path.  But there are details that were simply too small even for it, so they were ignored.

So it's not a problem with Slic3r either, it did the best with what it was given (another adage, GIGO: Garbage In, Garbage Out).

This is where your common sense should kick in.  These models are too small for your printer to produce a good print.

To prove there's nothing wrong with Slic3r, enlarge the model 3x, then take a look at the code.  Below is an image of the model sliced @ x3 scale.  You can see that all the details are there, including the ladder.  The yellow represents the support.  As you can see, it supports the bottom of the van, the mirrors, the wheel arches and the ladder.

BTW, this is the original model, with the inner shell removed, to make it solid, but didn't do anything else.

and as for " address your concerns with the program and it's shortcomings to the authors of said program" I tried that but never get reply likely due to being free apps. or in the case of Skeinforge there is nobody to contact and hasnt been for at least over 2 years. thats why most dont use it like myself.

and statements like this "As for new people being "run off" because of a few setbacks and/or crappy models? To me, those that are that easily discouraged don't really belong in the industry to begin with. " is why 3D printing will NEVER be user friendly/plug N play as many printer makers try to sell it. also why your last comment of troubles faced by yourself at the beginning.

We (users like on this forum) are not responsible for apps made/sold by makers of said apps that have short comings, as to files with errors on depository sites those are the responsibility of designers of said files if they will take that responsibility (not likely).or moderators of said sites to delete bad files so others dont waste time with them.

as to Win10, thats another issue that has lots of documentation online to support my posts and my position on it and MS. there are many thousands of people that feel the same or worse about it after trying it. its a very bad security risk to say the least.

not going off half cocked, I been working on these issues and researching the route causes for a couple of years and this topic is my conclusion of those findings. and I still dont see anything to explain it or prove my conclusions wrong. these apps are supposed to do the job intended and they have short comings in several areas of this. seems I am one of the few to discover them and say so. its not unreasonable to ask the makers of these apps to correct them to do as designed. even if just telling user "file is damaged or improperly designed beyond repair/use". instead of pretending to repair/slice and give an UN-useable file or Gcode to waste our time and material on.

I knew it was based on something in these models that slicers did not see nor Netfab and other repair apps.

You "knew" there was most likely a problem with the model, yet you slam the slicing and/or repair software as the root cause of all your problems?
That makes absolutely NO sense what so ever to me.

I am sorry, but it seems to me that you tend to go off half-cocked over things with very little provocation. You did something very similar over the windows 10 update thing not that long ago.

to start, Netfabb is spelled with two b's, not one.

As for what the different colors mean? easy - click on "Settings" in the menu bar, then "settings" again in the drop-down menu. About halfway down the window that opens is a "Colors" listing (it is under "General" settings if the menu tree is not open already), click the little + sign and it opens and lists all the various aspects and the color associated with it - you can even change the colors to something you like better by double clicking on them.

Perhaps you should address your concerns with the program and it's shortcomings to the authors of said program? Posting "alarmist" threads such as this one does nothing to help improve anything. (and the title of this thread is exactly that - alarmist)

See my comment above regarding contacting the authors of the program(s)...

As for new people being "run off" because of a few setbacks and/or crappy models? To me, those that are that easily discouraged don't really belong in the industry to begin with.

The people that really want to change and/or improve the industry will make an effort to do so in one way or another, with things like innovation and ingenuity. New programming, circuitry, hardware, software, and yes, even better models themselves. Not alarmist threads claiming bugs in software that aren't really even there...

Well thought out and well written tutorials/instructions are also a way to improve things.

For me, as a beginner a year & a half ago, trying to find solid, useful information that I could actually understand was like trying to find a needle in a haystack - it is so scattered or written with assumptions of the reader knowing what the author is talking about when, more often than not, a "beginner" most likely doesn't have a clue.

so while Pirvan done a great job here, several issues are still UN-explained as to why Slic3r finishes slicing without errors listed yet support etc are omitted. that is very UN-acceptable performance for even use by experienced 3D modelers.

and also brings apps like Netfab into question as to their performance/abilities if they think a model has no errors when it still has many. I already had issues understanding what errors are with Netfabs color coded messages just making all types of errors Red/yellow with no way to see or deal with each type error separately or learning what errors still need attention after repairs. now even when all is Green its in question as to if its sliceable/printable.

I want to correct this behavior in these repair aids once and for all, instead of just skipping half the issues or updating apps that still havnt fixed their bugs.

how can we expect new people to our 'hobby' to learn to turn it into a viable industry when we give them broken tools and copies of broken tools to do so? we must deal with all these "minor" errors in all repair related software until they are history before expecting to 'move forward'. either files are fixed completely are they cant be and need deleted and redesign new file and remove any that fail such tests from sites like Thingiverse. instead of running new comers off thinking thats the best they can expect or its their fault and not the designers or tools used to double check files.

One would think that if you keep having the same errors with different versions of a software one might actually consider the model as the source of the problem, not the software.  Or at least investigate the possibility a little more.

Just because something is manifold does not mean it is suitable for 3d printing.

but hey, I am not an "expert" by any means...

Take a look at the image below.  Cura, couldn't even slice the model correctly, because the lines would be thinner than the minimum extrusion thickness. 

Slic3r on the other hand, did manage to lay a single path down, but some of the paths are broken and would create free floating pieces.  In the circled areas you can see gaps, especially between the windows and doors, there are bad surfaces near the corners, where the side markers would be, the mirrors don't slice, the ladder on the back is missing the vertical bars, but has the horizontal rungs, etc.

maybe a zip

I took a look at your model.  The problem is that this model is hollow, and some of the walls are too thin to be printed.

I did a cross section of your model in both the X and the Y axis to show you some of the areas that will probably not slice, or if they do , they will most likely not print at all.

Take a look below at the areas circled in pink.

If you want to fix this, you should completely remove the inside walls, and make it solid, then let Slic3r or Cura define the wall thickness.