I used to be a Microsoft Certified Systems Engineer until I let my qualifications expire a decade ago. Been building and repairing PCs, doing corporate network installs and consultancy since 1990. I have been online since 1983. Compromised ads can and do infect computers. The fact it is a respectable site is not a safe guarantee that an ad is not compromised. In fact the situation is so bad it has coined the term "malvertising".
A recent example was the Zedo web ad platform getting compromised last month. That served ads to websites such as Last.FM.
http://arstechnica.com/security/201...ng-campaign-that-could-have-reached-millions/
It would appear that the qualifications you have aren't worth the paper they're written on.
