sadly... not much happens to them
I've reported a few scammers or even warez owenrs, and they still roam this place.

hence why I put that text in my sig a month ago, just do background checks and talk to them on the phone
you are putting a lot of trust in them, one guy that I'm sure will comment on this thread unless my reply scares him, has admitted to "borrowing" a clients DB within the clients knowledge... there are many worse things that have been done, just using that as an example
your data is the most important thing on your site, without it you have nothing, if someone takes it, they can make your whole site and email the members to get them over...
just be careful