Those are actualy old domain names with previous good websites. The owner could have given up on the domain or forgot to renew and another one buys it. Since the domain already has plenty of links pointing to it, it takes a while for Google to remove it from their DBs, hence it temporarily ranks it on whatever theme the site currently has.
It’s a good short-term strategy, but it fails in the long run. It’s an odd trick but not really spam, at least not more than link exchanges are considered spam.