Yes, I too have viewed a similar scenario. I know of a warez/porn website having Google Adsense ads and they have been getting monthly checks for the last few months. I will not provide the link, since I partially own the site, but I can assure you that Google knows about the ads and has not banned us for almost a year... This is an evidence of Google's dominance slipping away slowly....maybe negligible now, but surely it is slipping down...
they are using adsense in 300x250 size ads along with adbrite which is very confusing and i think they will get a ban soon
i have 2 hosts 1 for illegal activities that is offshore and another is for legal so i have hosted legal sites like Link directory article / Webmsn / imagehosting and pr tools etx
There is a little trick going on. Though these sites are using Adsense ads google will not even know it as it is being used with Adbrite.