So you create a banner ad, most likely to get someone to click on it to drive traffic to a location. Very few people use a banner ad for general branding (not to say that it's not a correct way to use them). Yesterday, while seeking out some information about a TV show I had recently discovered, I came across this PETA ad.
I'm sorry, but what is your target audience that wants to see David Cross naked? It sure as heck isn't me.
Had I not been in advertising, I wouldn't have even given it a second thought. But, really? Here's a nice example of getting people to actively NOT click on your ad. Although, I'd be curious to see what their CTR is for this...there are some weird people out there.