When you click on the guest's name and go to their profile, it will show their first and last name.
When we first started our Airbnb, a more experienced host recommended that we stalk our guests on Facebook, but to be honest, we just don't have the time for that. I think one of the best things you can do is price your listing high enough to keep away most of the riff raff. Also, have clear house rules posted on your listing.
We've had 9 stays through Airbnb and 4 through HomeAway and have yet to have a bad guest...and 3 of my guests had no picture on their profile.
If you are really worried about having a bad guest, you could include a security deposit requirement on your listing.
Good luck with your Airbnb business!