At the end of the day, voting is anonymous. We can't really tell you why any of the votes have been placed, for sure, unless we were specifically the ones who placed them. The closest bet is that Tim lost his keys, again.
I feel I should also point out that I almost always see a direct link between "why have my questions been down-voted" questions and down-vote; that is, I see a direct pattern of these questions being down-voted more after the question has been raised, either through meta or comments. We can see this has already happened, here; since my original post, the question I personally down-voted has had one of its up-votes retracted. Another of your questions has received more down-voting, as well.
When the result of commenting on the amount of down-votes, I could only see the votes as a form of attitude punishment, which is bad form in its entirity. When these things are brought up, in meta, we have to assume that some users are simply being directed to your questions, agree with the downvotes, but do not agree that they should comment on why they are doing so. I still do not agree with this, but it's better form than criticing the question entirely off perceived attitude. Regardless, we can see that this is somewhat of the case, here.
I will make comments where I have personally voted, below.
I have three questions that I have asked on the main site. Every single one of them have been downvoted quite heavily.
In essence, only one of your questions has been down-voted heavily. Both other questions sit at -1.
..to the point that I am longer allowed to ask questions (I checked out of curiosity;
As brought up in the comments, this is a temporary ban. If you do not need to ask any more questions at the current time, this is not a problem. Just ensure you pay heed to the feedback for future questions, as if it happens again, the temporary ban will most likely be for a longer period of time.
I asked in chat twice (and some nice people upvoted the questions to try and counter-balance what they felt were unfair voting practices)
This, in itself, sounds like a problem. Your telling us that the up-votes come from users specifically because they do not agree that the question should be down-voted, which itself is a poor voting practice. If you do not agree that a question should be down-voted, you simply don't down-vote it. You should never award a question with up-votes if you do not think that the question actually deserves up-votes. We also can't tell, now, if anyone thought your question was useful, given that you've told us the up-votes were placed to negate the down-votes. I would not mind having a mod comment on this, as such practice sounds like the sort of thing that would even be revoked, if a pattern was picked up.
I personally down-voted your question Why is game maker displaying a model without all of its polygons?, and did so for numerous reasons. I did so a mere 2 hours after your final edit, and can recall leaving your question at -5. As such, it appears that even this question has been mostly untouched, since your final edit. Ultimately, I voted that your question was unclear and un-useful.
If you were to improve the question, you could consider the following:
To quote you from the comments, "@liggiorgio I'm not actually running this in game maker. Read the post very carefully. This is a mod of a game maker game".
I had completely missed that you were not asking about using Game Maker, the first time I read your question. Your telling us that you think it was made in Game Maker 8. That is not helpful, especially if it is not important. You say it should not be important, but why do you mention it? It is good to remember that if the information is not important, it probably should not be there. Useless information can detract from useful information, and make your question look overly cluttered.
Your question appears to continue providing unhelpful information further down, where you appear to reprint duplicate code, simply for the point of presenting it in a more readable format. If you think that your code would look better presented in a different format, only present it in the different format. You can still refer to it, earlier, as "code snipper 1" or "my first code, below" or whatever.
If I were to improve the question, I would consider the following:
Please take this with a grain of salt, but I would personally delete the question, if it only came down to quality.
When it comes down to it, you were having a problem with a mod created by SomeGuyTM. When you have little information about the origin, it makes things particularly difficult. We do not know if SomeGuyTM is even remotely good at game developing, so for all we know, your problem could have been any number of inconsistencies resulting from author error.
At the end of the day, I'm confidant in saying that the only reason this question found an answer was that you were evidently able to find the answer without GameDev.SE. While your answer does point to something interesting in GameMaker (at least, in my opinion), there is simply not enough information in your question to accurately pinpoint the cause without personally playing around with your project. This is still a problem: How would anybody experiencing the same sort of problems find your question? Not very well, I would say.
Lastly, with a vote of -5, your question does not appear to regular users. As such, not many users are actually going to be able to up-vote. You have to ask whether it is worth cutting you losses. If I am not mistaken, you actually earn a medal for deleting a question with severe down-votes, so it's not all bad!
There is another option
Ultimately, you found your answer, so your not worried with attracting more attention to answer your question. You could tailor it to make it easier to find, if other users are having the problem. It appears that the problem was related to the mod being made in an earlier version of GameMaker. Why not rewrite the question to focus more on the fact that your importing a model into a GameMaker mod and having said problems?
From the looks of the answer, I suspect that your code had nothing to do with it. If that is the case, remove it. All of it. It might seem useful, but it might also detract users who know their problem is not a code problem, and immediately assume that yours was.
Make it short and sweet, and again, focus on the core problem. You might consider making the title more specific, as this is the first thing users will see. Something like "Why won't my model display properly in a mod made with an older version of GameMaker". Than, you could say "I know it is an older version, but the makers have unfortunately provided no specific information, and are not responding to my communications."