I zapped one of them. (Someone else must have done the other one)
The person who's posting those threads couldn't care less whether they anyone here reads them or even whether they make any sort of sense at all. He simply knows that Google is constantly checking this site. (If you google for a question that was only posted a minute or two ago you'll nearly always find that Google has already indexed it).
He also knows that Google pushes website listings up its ranks based upon the number of links to them that appear on other site. So, if he can get links to the websites that he's being paid to promote dotted around all over the web, those sites will be pushed up Google's listings and he'll get paid for the happening. (It's called 'search engine optimisation'). He probably doesn't even care that his threads get zapped within a minute or two; as long as Google has already spotted the link(s) in his post he will have achieved his aim.