The more you use the system, the more you'll trust the results. Instead of ads being something others are pushing on you against your will, they become something under your control.
They're your ads now, not theirs.
You'll also have more awareness of the ads, because advertising becomes interactive. The more you interact, the more you'll pay attention to what appears there, and that boosts ad response for Google's customers, the companies that advertise.
And finally, user awareness and control over advertising improves the Google experience. You can block horrible, annoying, inappropriate and offensive ads. And once you do that, you'll like using Search and Gmail more.
Google's motto is: "Don't be evil." And you'd think that ad transparency is a result of that creed. Maybe it is. But it's really about being smart. By co-opting users into the ad selection process, and giving them a sense of control, Google brings attention to advertisers, gathers better data on users and makes users happy not just about using the sites, but about the advertising itself.
Facebook? Not so smart. When I see the almost always irrelevant ads on Facebook, I feel powerless to change them.
Instead of a "Why these ads?" link, Facebook offers a link to "Create an Ad." Instead of "control what you see," Facebook says "give us money."
Facebook's sneaky approach to what data it gathers, and why it's showing me the ads that it does is just one more thing for the list of why I hate Facebook.
Even worst than Facebook are countless blogs and other sites that have truly repulsive wrinkle cream, weight loss and other ads that make you wanna holler. Your only recourse is to stop visiting the site.
Google is smart to pursue this avenue of user engagement around advertising. And users will be smart to participate.
In fact, the only way to improve upon this is more, more and still more. I'd love to see Google ad ever more user control of advertising.
Also: Google should roll it out to all sites, and even AdWords. Other services should get a clue and compete with Google on advertising transparence and control. And users annoyed by advertising should get in the habit of choosing the services they use in part by how much control they're given over advertising.
After all, only unwanted advertising is bad.
When ads show me the products and services that I actually want, it's a service, not a nuisance. And everybody wins. And that's just good business.