From: "Tony Sidaway"
I'm suggesting that it's not around in significant amounts. I find some now and again. I find instances of poor quality writing and bad organization more often. A few articles are prone to link-spamming, others get POV-pushing. Compared to that, old vandalism is rather rare.
The kind of old vandalims that I find particularly disturbing is stuff like this http://en.wikipedia.org/w/index.php?title=Robert_Bunsen&diff=23686756&am... which occurred on september 21, then was edited in by 2 more editors, until I reverted it on October 5th. The reason I find it particularly disturbing is that the anon only ever made that single destructive edit, which was not only not noticed but actually totally ignored by the next 2 editors, and I only noticed it because I thought it was odd we had such a crap article on an important person. If he had been less important I imagine no one would ever have noticed.
It is stuff like this that really makes me think there must be a better way than having a policy of "Anyone can edit".
Martin