I don't think ad copy means too much on Overture based on my experience. On AdWords, yeah- but on Overture, ya have 2-4 sponsored listings lined up that relates to the search term.
There is no penelty for a person to simply click a link. So, I really don't think folks take any time to discern between good ad copy.
I don't. Good ad copy doesn't mean it's a good website. Bad ad copy doesn't mean it's a bad website.
Ya gotta click 'em all to find out.
Sure- it would be best to optimize your ad copy...it may help for a small % of users.