It does happen, but it's never happened to me.. All you have to do is report and send a link of the original drawing and DA is pretty good at taking it down and banning art theft accounts
Main thing to worry about is buying stolen adopts so read through the comments well and see if the poster's art style doesn't vary as if to say they're posting from other people or if they just joined and started posting adopts without any links to main accounts(just trust your gut!) to make sure you aren't jipped
I think you'll be fine in that matter, however uvu thieves usually target popular accounts whose art has been seen by more people
Then what about commissions and requests?Cause I don't actually know if commissions done by points are done with money [the points being the money]and if requests are more than likely to happen if you have alot of watchers