If you followed my last blog about craigslist classifieds, you would of read how spammers are now in the craigslist arena.
The good news with craigslist is that the classified community for the most part police's itself meaning anyone can block out ads that are not legit. The problem comes when you respond to an advertisment such as an inquiry for a car only to recieve an email from an auto reponse account telling you that he or she has already sold the car but would like to extend you an offer to go to another site to buy a car.
A video a while back from the infamous Rich jerrk had this tactic on one of his sites telling people on how to drive traffic to a site using black hat tricks(this is an unethical way to get people to go to a site)
The techniques goes with the user looking for an affiliate program in click bank for dog training.
The user then gets the affiliate link and creates an email similar to what I mentioned telling the responder that the dog has already been sold or given away but please go to so and so website on dog training.
The good news is that this tactic has slowed somewhat on the craigslist site but it hard to detect if you responded to more then one classified.
Just remember when responding to classifieds, use another email account unless you want your primary account full of spam.