5 times more likely?
Yeah, you are 5 times more likely to click on an overlay add. Mainly because the close button won't be in the top right corner, it'll be tiny, and it'll only appear after a few seconds, (Or not at all as is the case most of the time with facebook).
Adverts are all well and good, but most people just want to ignore them, and while other sites are offering the same service with adds you can ignore, or no adds at all people will move to other providers.