Pop-Up ads, more likely or less likely to buy from the company?

Just fought several whole page pop-up adds and it got me to thinking: How much business do these things deter for both the paying advertiser and the revenue generating website?

Quite honestly, any website that gives my computer pop-up AIDS gets blocked, and furthermore, the company that chose to advertise through a pop-up ad definitely receives a negative connotation in my mind.

So what do the oh wise ones on the OT say? Good or bad policy for companies? It's not like a TV commercial where it's expected, these frickers pop up out of nowhere.