Why would you want to trick the surfer in to clicking on an ad?

I dont see the need for these personally, these have been used and abused by spware companies for years they are nothing new and personally, whilst they may increase clicks to a site, i dont see any reason they would increase sales, in fact, i would guess they would have the exact opposite effect, i know whenever i get one of these popups on a site i close my browser immediately.

Regards,

Lee