The problem with ads is drive by installers, many worms and trojans are deployed that way and no ad service can really stop it.. if they even bother reviewing the ads the bad guys just put up an ad with external refs... it looks clean until they change the external server to deploy malware and bam.
Do they have an alternate url for these ads?.. I do 99% of my browsing through privoxy.. and it blocks those ads because the domain contains advert.
and fifth post so everyone can see an example vvvvvvvv

Can you elaborate for the layman?
re: drive by downloads/installers?
Wikipedia has a short article on the subject:
https://en.wikipedia.org/wiki/Drive-by_download. Basic gist is exploiting a browser/os weakness to install software on the users machine without user intervention. These are usually targeted at popular search terms, for example when the latest ipoop comes out.. almost a guarantee that some ads/paid search results for that term will have this type of payload. There was some big football thing years ago, I had 5 people come to me with Trojans.. all they did was search/view some pages related to the football game or soccer..or whatever it was ;-)
Ad services generally do not require all files for the ad be hosted by the ad service (why spend the money for that), rather the ad service serves up a reference to the ad on another system.. or otherwise serves the files from the ad customers servers. Because of that the ad customer can change the ad contents at any time, and unless the ad server is actively monitoring (again, why spend the money..) a nefarious person could deploy drive by installs that way. It's fairly common.
Presumably you're not talking about the ad being blocked..