When I first joined the site and I sucked at renders, mine got taken down. Like Seth said, I just used the paint brush tool, and they were awful. I would post a link but it won't let me access it. Hope that helped!

The diffrence between the two are that bad renders can be when you don't have neat lines. Its up to the mods if its neat. Your renders are neat then. Neat renders are when you work your hardest and make it your best. The mods can tell if you worked your hardest. They can just go back and look at all your work. If it looks like your work, then it will be exepted. Hope it helps!

I guess I would say amount of effort one put in. I guess if you just color over image quickly in Paint with brush tool doing zig zag lines, so you can still see backgrounds on some parts, or you did minimal changes, for example just add one marking on lion and call it complete and stuff. I guess that would be bad render.

It is not so measured by skill, since people of all ages are visiting site and all, but I guess it is up to mods to be critic of when sender is just young and he did try his best or when it really was lack of effort and stuff like that. Since it is really hard to exactly define which renders are not good enough, without having problems. So they just said bad renders, it is bit subject to personal taste, but it is best way to describe it.

I hope that makes it clearer. At least that is how I think it is.

A bad render is a render that is quickly made. Like they just took a big brush and colored over top of it.