Bryan Eisenberg wrote about something I always wondered about - when does having a pretty face on an ad help the most at GrokDotCom in a post titled: How A Pretty Face Can Push Visitors Away:

In the heatmap of two almost identical ads, above, the ad in the left works better than the ad in the right because the model in the left picture is looking at the item being advertised while in right picture, she's not.

I really responded to this post (maybe it was due to the pretty faces)!