I don't see the ads anymore either, but back in the ancient "pre-supporter-feature" olden times, this was one of the more commonly recurring threads. No where near "hair versus smooth" or "is bisexuality real" mind you, but still, probably in the top 20.
To repeat the answer given all the previous times (I'm to lazy to search for the old threads on the typically crappy forum search engine) -- no human is controlling these ads. Computer servers somewhere in the cloud are looking at all the text on each thread's page and performing statistical analysis of which ads might get the most click through on such a page. Like all statistical algorithms, 70-80% of the time, they do a fine job. The other 20-30% looks a little strange to us humans.
During the 2008 presidential election, this question came up every few weeks, as readers derived bizarre plots trying to explain the computer-generated placement of Repub or Demo ads in RJ threads.
Sadly, there is no "secret Republican plot" or anything like that going on. Just a bunch of programmers trying to maximize Internet ad dollars. Quite benign.