What do you consider "safe" to buy off Craigslist?

Lots of people rely on Craigslist to get clothes, furniture, concert tickets, electronics and even cars or pets. Personally, I have bought an air mattress off Craiglist, and I’ve also sold a printer. However, I don’t think I would buy a car or a pet, or even a bed. I don’t think I would buy electronics unless they were brand new.

What would you personally buy off Craigslist? Anything goes? Or only select items?