I'm not convinced that "Do no evil" applies to Google's handling of advertisers. I've seen it happen that some small company will get its ads banned, and all Google will say is Google isn't sure the company is legitimate. The company makes no headway getting it resolved--until they go hire expensive advertising consultants to manage their Google campaigns, and the consultants have not trouble getting Google to review and reverse the ban within a day or two.
My biggest frustration with Google's motto is that it is not "Do no evil" ...but that it should be.
Their motto is "Don't be evil." I'm sure it wasn't an intentional weasel, but it does allow a lot of weasel/wiggle room, as in: I could not in good conscience call the whole outfit 'evil' - but I worry about some of its specific behaviors/policies having evil effects. [/rant]
My biggest frustration is that people care about the motto of a public company. It doesn't matter what the motto is, they're in this to make money. They're not going to turn down billions of dollars because of some nonsense written on a wall.