I think it may be possible to buy, and act like mannequins. But the only limitations is that you can't put something offensive in it as a way to bypass the filter system, and well. There may be some so I'll leave some reasons for someone else. Also cool idea.
I know people who push Billy out of the top 5. I can 100% guarantee 1 person that is richer then billy and would take 4th. I know others that are most likely richer then billy as well. Billy is probably 6-8.
We are not supposed to use them. That being said I think it was only so it wasn't spammed. I'm sure if it becomes a problem, someone will deal with it. I'd say just don't do it, but I know a lot of people will anyways, so for their sake, I say don't OVERuse it.