Sometimes I come across violations and if they are really obnoxious and blantant (scraped content, nothing but ads, misleading pages, etc.) I report them to G. But sometimes I don't if they aren't too bad (ie, quality site but has images right above content; Or, title right above ads). What do you think... should you report every violation you see? How will G handle these reports-- ie, warning people, or just banning them? I'd hate to see a nice site with just a small offense banned, but when sites that are pure junk get banned, that's great.
I used to report violations but now stopped. Google never takes any action. Now I only fax them DMCA, if something is related to my own site.
Never. Firstly I consider it "snitching" and secondly I don't feel the need to police Google's multi billion dollar empire for them. I wouldn't waste my energy worring about what the other guy does. As long as I'm happy with what I do is all that matters.
I used to do it many times, strangely after doing it for a website for a whole month (warez website), my account gets banned - MY ACCOUNT :S. Now I learned my lesson, don't bother Google, Google doesn't bother you. Peace,