Wikipedia actually dodged a nasty bullet, because once the bogus quote got into a newspaper, the "quote" in the news story could then have been cited in the article and thus be protected-- at least until the truth was revealed.
I edit in Wikipedia, and I keep a bunch of articles on my watchlist-- which is to say, when I ask, I get a list of recent changes in those articles. I've only dealt with one bogus citation, which was being used to defend an urban legend, and it was difficult to chase down because I didn't have direct access to the supposed original source. Of course, someone else fought me the whole way on it. Still, imperfect fact-checking is better than none at all.