Re: I like polluting Google's data set
That would make a nice add-on for someone to write for Firefox (hint hint)
Just set it loose going to sites from your site history that use Google CRAPTCHAs and have it click random boxes for a minute and then abandon it. It would need to be clever with random delays and varying behavior so Google couldn't suss it out. Maybe even fake the browser identification to claim it is Chrome so Google can't simply ignore non-Chrome users.