maximillianos - 6:49 pm on Oct 23, 2009 (gmt 0)

As others have pointed out, I think a sweeping block of placement-targeted and certified network ads won't yield many positive results

Agreed. It is a case-by-case decision. For us, we started seeing weight-loss ads in the 1-2 slot on our 4-slot ad blocks on every page on our site (last Spring). It was completely off-target and looked very spammy to our visitors. I didn't care how much they were paying (which wasn't much). We didn't want the ads. We tried blocking them on per-advertiser basis... but they were using so many domain name variations it become an impossible task.

We talked with our Adsense rep, and were advised that the only way to truly stop it was to have the placement targeted ads turned off for our account completely. We were told that even if we blocked all the advertisers directly, they could still target our site via "category targeting" which we cannot control. And the only way to stop that was to turn off placement targeting all together.

So long story short, we had it disable in our account and have not used it since. No more weight loss ads... =)