Gilles, sorry for taking so long to reply here. By calling that scenario unrealistic, I was arguing that the 25/-15 example is a (probably intentional) exaggeration (first illustrated by Monica). I don’t mean to say that answers containing wrong information aren’t upvoted (they are!); my point was that, whenever a post gathers any significant number of votes in one direction, the difference between upvotes and downvotes increases. 25/15 is a 67% delta, and since 25 is already a fair number of upvotes, examples of this specific score distribution should be quite hard to come by. They probably exist but should be very rare in my experience. But then again, I should observe that due to reputation restrictions, I was - until very recently - only able to see score distributions on Stack Overflow and not on any other site, so my experience is definitely biased. Even more so in comparison to yours 
Anyway, sorry for not making my previous post more clear!
P.S. I can’t see the upvote/downvote count for the example you provided (thanks, btw) - how is Jeff’s answer scoring these days? Just out of curiosity, if you don’t mind ^^.
(Please check this as well, @YLearn, since you addressed me on the other thread about this.)