I think google has a program with partner sites and if the advertiser has opted into the program it will place your ad on random sites that are deemed to be related topics. Not entirely sure, but what may be happening is the pirate sites join into the partner program saying they want to get paid for hosting ads, and the micro sites are in the program saying they want to be placed on related sites. In many cases they are being placed on sites that are photo blogs and forums, but in this case they are ending up on undesireable locations. I don't think you can select, it's probably all or nothing so to eliminate those you'd be eliminating all the desireable sites by opting out.