TheBigTroll,
That is something we are considering. However, in our experience, the spam accounts created on Tom's aren't created by robots. Even though the posts may look robotic, since we have a custom system, its not likely that robots created the accounts and posted. Most of the spam companies have armies of low paid people to do their work for them.
Some of our other sites do have captchas but pretty much get the same spam. That's why we feel it is still being created by humans.
Something else we are working on rolling out soon is a junk filter. That should catch most spam whether it is posted robotically or not. That should be coming out very soon.
Thank you!
Justin