The only way this can be proven is if people post pictures of their BPs and have people vote =]. Or what could be really fun is if at a reptile expo, they can have snakes on display and people vote which one is nicer ^_^
I guarantee that it won't be a 50% vote LOL. Some traits are more sought after than others which answers a lot of questions. When people ask "what should i look for when buying a pastel?" You can reply "most people prefer X... but I prefer X..." but at least you can say most people will agree on a certain trait of a named morph...