I guess the issue is, does Google know when someone recycles a captcha, and if they do, are they doing anything about it? It's useless if the captcha isn't flagged and is just given to another use.
This is Google, so I'd imagine they keep tallies.
The tricky thing is that there are hordes of automated captcha-breakers that will recycle captchas until they get something that's easy to OCR
Yeah, and a couple days ago I had to hit that button about 20 times before I got one I could decipher. I was about 1 or 2 clicks from giving up.