Persistence is a Virtue - but pop-ups are a pain!

In the Fogg book, one of the areas of ethical uniqueness is that computers can continue endlessly, without tiring, in delivering their message. They use the example of certain pop-up ads that are so persistent in their delivery that, eventually, subjects just give in and begin clicking. While pop-ups are up there with the most annoying things in the world (aside from that sound you make when you're really thirsty!), I don't see this as an ethical question. If pop-ups circumvent pop-ups blockers, then I can see an ethical dilemma. If someone requests not to receive pop-ups, and they do anyways, then their is a problem. However, I fail to see the correlation between ethical questions, and pop-up ads.