Habtom - 8:07 pm on Feb 14, 2012 (gmt 0)
I do NOT check to see who is advertising on my sites via Adsense and then contact them at all, ever. In fact, I've never gone out looking for advertisers. They always find me. How they do it is their business.
I don't think anyone has a complete list of advertisers on their sites. This shouldn't be an issue at all.