What is Left?
You do Adwords Marketing, Right way or Wrong Way. Right way is strictly following all the guidelines in letter and spirit. Google adwords was created in such a way to reward the honesty and punish the wrong no matter how sneaky they are. It was true in the initial phases of adwords marketing. Google has broken the mold it was cast in, long back. Right Wing practitioners of adwords marketing who bought into the idea of radical honesty on internet marketing should be alarmed or be ready to get edged out by ones who are not right but fits into Google's scheme of doing the semblance of legality, hence not wrong either. Prod at Google for quality check falls flat.
Free Voucher Economy Thriving
In fact good number of agencies have made fortune out of free voucher program. A little gaming with the system allows them rake in huge profit by quoting to advertisers at the fraction of Click cost & running adwords at zero cost. Google's benefit is, they help push the click cost in auction upward and make some honest advertiser pay higher. Google has altered TOS for applying these vouchers to pander to these bad boys of PPC. When I last checked Terms & Condition, I could find this poorly written document with a conspicuous grammatical mistake, promising credit in your account after "an minimum" spent. It tells on them, how much analysis has been done and how many people actually care about reading it. Clearly, Google didn't even check it again after posting.
Tech Support ads still run
Its an industry created by Google. You know Microsoft Bing pulled itself out of this murky business by categorically declaring Third Party Tech Support won't be allowed on Bing Platform. It is in black & white and talking to Bing support I felt they are in no mood to cut you some slack. In contrast, Google has no cut and dried version on this business. It continues to play fast and loose on this front. Most of its sales partners, SMB, Google authorized, blah blah.... were heavily dependent on this industry and may not like to be saddled with other kind. So, you still find some ads in this category running on Google, terms of which are not above board.
Double Serving is an art
Google in 2008, relaxed double serving rules. It has four points out of which at least two should not be breached. 1) Two websites should not be owned by same person. 2) Brands & Logo should be different. 3) Pricing difference should be more than 25%. 4) It should not lead to same customer support experience. If co. X & Y, points you to same customer support after buying then they are one and same breaching the fair use policy of ad network.
Despite all said about it. It is considered an art by many and Google turns blind eye towards them. In fact some agencies, close to Google, are considered specialist in this area. Talking to some advertisers, it was revealed, Google recommends them or rather they are "Authorized".
It is the common observation of PPC guys around the globe, if your ads run 24x7 and you are willing to pay a decent amount to Google then Google seems more than willing to cut you some slack. They only pick on small advertisers.