The real humans who visite those faucets, the just want the satoshis and do not care about ads.
And the many bots who visit faucets even care less about ads.
To me it makes no sense to advertise on faucets.
That's true of just about all advertising ever. I'll give you three examples:
1) Commercial websites. You go to CNN for news, not the ads; you use gmail for the service, not the ads placed in them. The ads just support the business of delivering news or e-mail.
2) People watching TV programs don't care about the ads, they just want the program. The value for the advertisers lies in the fact that people see the ads, regardless of whether they want to or not.
3) Nobody really cares to see or seeks out to see billboards on the side of the highway. There's usually never anything terribly interesting on them. However, that's valuable advertising space because so many people see them anyway.
In summary, advertising is a numbers game. The more eyeballs you deliver, the more valuable your advertising space is. Nobody wants to see the ads, but that's not terribly relevant. The only difference for faucets is so much traffic is generated by bots, and bots don't have eyes, therefore provide zero value to advertisers. This is why incentive-based traffic (like faucets) is prohibited by AdSense and other advertising networks.
But that has nothing to do with people not wanting to see the ads.