Yes, when you visit some sites that advertise Google adsense, Clicksor, yahoo, bidvertiser...And you know how pay-per-click works, you see something interesting in the ad of the site, will you CLICK it?
Answer truly please, when you click it, the site admin will profit from your click. I think anyone has a little selfishness, but bases on a little or much.
Give your opinion. For me, i will click if the site that i visit is my taste.

Not sure,

If the site is doing GREAT...then I might give a click

If the site is poorly based...I wouldn't =/