And I spent several moments considering that, and then it occurred to me that it couldn't possibly mean what I'd initially thought, and so I was considering what else it could mean... and... Yeah. Whoo...
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Back on topic, since I'm here, as a totally ignorant user I'd have to say that I'm more inclined to click on an ad I've seen before, figuring that if it turns up again, it's probably more relevant.
But, again, that depends on the situation, and I'm still working on overcoming my banner-blindness to actually click on the adwords ads in the first place.