Ad clicks cost, sometimes. But sometimes they send a positive quality signal resulting in reduced costs to run that ad in the future.
(Or then again you might. Because you'll screw up their A/B testing stats. Or you might not. Because if they have half a brain they'll be running conversion testing anyway and they'll easily spot a high-CTR, low-CVR ad. Or...)
Anecdotally, I've been seeing lots of political ads lately.
(Digression: I always click on the ads for candidates of the party that I despise.)