We regularly get those sort of listings (very desirable cars for insanely low prices) on our local Craigslist. They only last a while before being flagged into oblivion. In some cases, if one searches for the e-mail address using Google, one finds that the same ad showed up in Craigslist listings in a number of cities across the country.

I've always assumed that they're some sort of scam, but I've never investigated further.

We also have some ad-flagging vigilante who flags apparently legitimate dealer ads into oblivion if, in his opinion, said dealer has been putting up too many ads.