I've been reading some of the Adsense cancellation threads here. At least one of them blames their Adsense infraction on user-generated content found on one of their pages.

This problem had never crossed my mind (I don't have any UGC on my sites).

I had considered implementing a "comments" section at the page bottom of some of my articles. Now I'm thinking this isn't a good idea at all.

Whose showing Adsense on pages with UGC? What solutions do you use towards preventing problems?