buckworks - 6:40 pm on Sep 3, 2012 (gmt 0)
Does this mean that advertisers are being ripped off?
No, it doesn't. Advertisers only pay if their ads get clicked.
Interest-based ads are not spewed around randomly, which some people seem to think. They show up because the algo has reason to think that particular user would be interested in that particular ad, AND the advertiser is bidding high enough to get past whatever ad(s) would otherwise appear from normal keyword/theme targeting.