There are a lot of Scammers out there, You can just Google online dating Scammers, and all these websites pop up with their bogus pictures, Its quite good, I have recognised 3 so far. So if someone doesnt seem quite right check them out.
That's a fab idea. You simply type in their online name and it pops up as a scam? I get ladies who don't write english well (they are probably guys from Nigeria) who claim they are in Africa and eventually ask me for money to get back to the U.S. Ya, right!
Tineye is also a good resource. It allows you to find images on the web and where else they are posted. It is rather limited at the moment, but can be a help in identifying and deciding if you need to red flag an account.