As far as I am concerned they use Google Ads for advertisement, so, if you want to blame someone, blame Google Ads. I don't think coinmarketcap wastes it's time verifing all the ads that display on their website.
You are right. I didn't see any privately sponsored ads there. All ads are from google. There is no fault of CMC. Moreover, google place ads as per client's previous history. However, you can blame Google here.