These pop up every know then, and I'm having a feeling that they're not allowed since they're basically asking the worker to post spam. Can anyone confirm that they're not allowed? For fun, I tried doing one of these HITs, but as it turned out, you need a US cellphone to activate the Craigslist account, which I don't, being a Swede. And besides, spam is bad. And if these are actually not allowed, there's a good chance that you won't get your payment either. All in all, avoid these, and possibly report them as violating the policies.
You will soon learn to weed out the bad from the good. There is a lot of spam but if you keep digging you will link onto the non spammers.