I'd **** to be the man to try and create and maintain a true database of who looks like who. When you see "if you like x, then you might like..." the results of the search are usually linked to general tags. So the person never actually looks like the person you want, but has the general features, such as height, hair color, ethnicity, etc. All of which, you can already search on.
I've thought about this and thought that perhaps measurements, ethnicity and hair color would be more reasonable for a "she looks like" type of button. maybe?