My site's always had great Google placement, but it took weeks of bad behavior by Bad Behavior to alienate Google which has dropped me from its listings. BB's Michael Hampton admits his WordPress plug-in has a bug that rejects Google site crawlers as imposters.
"You claimed to be a major search engine, but you do not appear to actually be a major search engine" Bad Behavior repeatedly told Google crawls as documented in multiple view-as-Googlebot errors at Google Webmaster Tools.
"I'm pretty sure this is a bug in Bad Behavior, but I haven't been able to isolate it yet," emailed Hampton on November 10. "For the moment I suggest you discontinue using Bad Behavior until I find and squash this one."
I've so far been unable to lure Google back to my pages after weeks of rejection. I've filed a request to reinstate my site, but Google says it'll be weeks before anyone gets around to reading the plea or acting on it.
I strongly advise any Bad Behavior user to perform a view-as-Googlebot search in Webmaster tools to see whether Bad Behavior is rejecting Google searches.