Either they do or they don't. A quick google didn't turn anything up, but does someone have a reputable source?
https://blog.malwarebytes.org/malvertising-2/2014/09/googles...
http://www.mediapost.com/publications/article/247982/google-...
http://www.csoonline.com/article/2924309/malware-cybercrime/...
http://readwrite.com/2014/05/15/app-redirects-mobile-spam-ad...
As far as I'm concerned, no need to be polite with Doubleclick. If they're serving malware, they can fuck right off.
Either they do or they don't. A quick google didn't turn anything up, but does someone have a reputable source?