Yeah, I had a friend who was here all the time and had a tendency to draw sexy avis wearing the pasties or next to nothing. He got banned, but was able to come back.
When in doubt, ask a mod. If you're second guessing on a particular piece, it may be wise to just put a warning up and link it rather than fully posting it. You can even make a thumbnail of a "safe" part as a preview that people can click for the full view. Just be sure the post a warning before the thumbnail and ask a mod if you're unsure.
Obviously, I'm all for pin-ups being posted since I draw them too and they don't bother me. Especially since Gaia doesn't seem to abide by their own PG-13 rules when it comes to some of the items. But I'd rather not lose my account either, so I protect myself.