I think it depends on if there is an R in the month and wind direction basically.
A year or so I pointed out about 20 odd sites doing this (I was bored that day!), and they dealt with all of them. 19 complied, one failed to comply and got booted.
Recently I've seen an ad (on my site of all places) who'se landing page broke pretty well ALL the rules (including disabled back button) and it asked visitors to click ads. No amount of emails to adsense and adwords would make them act, and the ad was still being served with the "click the ads" line until recently when QS seemed to have killed it off.