I've been "captchaed" with Chrome, so I'm not sure the anecdotes amount to much.
That's interesting and useful to know and I decide to believe you.
BTW: Yes, I absolutely noticed that you said this above:
> ...and the beauty of the Internet is that there's really no way to be sure people are being genuine...
My point is, unless the claims of the others are outrageous or we have something very specific to point at, I don't think voicing these kind of thoughts do much good.
I've at least been "captchaed" in Firefox. While being logged in with my Gmail account from 2005.