This is one of my issues with Turbosquid's version of this as well. I see the value in it but it's also the issue you run into when you have a wide range of ability levels.
Some things that I see as a mid quality product (for whatever reason. Lack of images, quality in general, etc.) could be someone else's highest ranking.
The way I think squid fixes this to a degree is to show the average ranking for a piece after you've voted. It shows how off the mark you are on a piece and give you a bit of feedback if you should be more hard/raise or lower your standards.
But even then you are leaving quality rankings up to an unknown pool of people. It's still a good initial filter though at least.
I think so many guidelines like Ricardas mentioned may be hard to enforce unless you break each piece up into multiple rankings then average them. For example a piece would have, instead of a 1 to 10 ranking alone, a list of rankings from image quality to model in general, etc. then average those up and there is the pieces final rank from that user.
BUT I think restrictions on model uploads is a fantastic place to start and remove some of the guess work. Requiring x number of images, etc. Then you wont have to vote on those and you could probably narrow down each piece to just a few key things to vote on.
If a model came up and you voted on core things like 1 to 10 model quality, 1 to 10 presentation, 1 to 10 would you purchase this item
something like that. Just tackling it from both sides with upload restrictions and then voting on multiple facets of the upload instead of one overall vote.
Either way, it's great to see you guys improving the site. I know this kind of system is a lot of work and getting criticism in the first few days sucks as a lot of it is normally knee jerk reactions to something new. Still, info is info. Thanks guys!