docbird - 1:16 am on May 8, 2010 (gmt 0)
The Google answer does say:
You can opt out of showing ads that are based on user interest categories (e.g. 'sports enthusiasts').
- which seems ok. I'd think only a v small proportion of my visitors would have interacted with advertisers.
I tried turning IBAs off during last month, after visiting thread about adsense revenue tumbling. My sites small potatoes, so result needs taking with pinch of salt: but CTR etc much the same, and earnings still low compared to previous years.