Inasmuch as clicks are a valid metric for advertising performance, it is only because they prove that an ad is prominent on a page. So in that sense, there's really nothing wrong with accidental clicks.
Companies that I have worked for have developed models (approximate) to remove accidental clicks to prevent charging the advertiser. Usually, these clicks are "absorbed" into a CPM though, and detecting accidental clicks is very difficult and requires many assumptions about user behavior.
