The about.com example shows how hard distinguishing quality algorithmically gets at the margins. You do actually find stuff on about.com now and then which is pretty decent--not great but decent. You might even say the same of ehow, albeit at a much lower rate.
On Quora, the former owner of eHow recently wrote[1] that when he handed over the keys to the people who bought the site, it had an excellent quality of content. This gave it a good 'credibility' on Google. When it was taken over, it was turned into a content farm, but the atrophy of credibility is possibly to disproportional to the spam parameter variable, which leaves it in Google's results. At least according to one of his listed explanations.
I recall about.com as a decent site a while ago, but I believe it was acquired a while ago by ... Yahoo!? Go figure.
So you don't want to just say "these are spam."