Many users are exiting websites without even glancing at the content. Why? Too much junk: ads without close buttons (or ads where the close button is really a link to the site being advertised), keyword popover ads, and extensive use of flash instead of content.

So, why do websites do it. Guess. Money.

Well, those advertisers aren’t getting my money. Like telemarketing, it’s just another form of spam.

http://www.ryanblock.com/2007/08/an-open-letter-to-friends-and-colleagues-on-keyword-popovers/