1. Clicked on page.
    2. Took maybe 10 seconds to take in what is "above the fold".
    3. Scrolled down to see what else there is.
    4. BAM! Popup triggered by scrolling down.

I will say, generally, when I'm to the point that I'm entering credit card info, I've put up with it, but I have been chased off of sites by this use case before. Especially if that popup also crosses with some other popup and now I'm chasing down the tiny little 6pt light-grey-on-white little "x"s to click away the popups in the right order.

Actually, let me add that to my touchstone list. OF COURSE hiding the dismissal icon for the popup increases "engagement" with the popup. You don't even need to run a test for that, because what other result could it have? "We shrank the close icon, moved it to the lower right corner where nobody expects it, and made sure to kill the constrast even harder, and customers dismissed it 2.5 seconds more quickly on average"? Of course that's not possible. But... that's the wrong question! And AB testing is really good at answering the question you're asking, it has no mechanism in and of itself to see whether you're asking the right question. If you're getting down to this you've overoptimized.