I'm pretty sure the adverts are generated using information gathered about the other sites you visit, things you look for on search engines etc...you naughty, naughty boy!
That being said surely they should have certain categories set not to show, typically amateur of TNT to miss things like that which I'm sure would be simple to avoid. I recall someone posting a screenie of sex toy adverts on there...and I saw one for a Muslim only dating site which I promise that I had not searched for on Google... xD