Being vain is not a good thing, but being honest is. If you look good, then you look good. If you look bad, then you look bad. People can't help if they look good and deserve a 10, and they can't help it either if they deserve a 1. Either way, it's all in good fun.
Yeah but you just said looks are subjective, to some people you may look good and to others you may look bad, how can you say what a person 'deserves' to be rated as? How can you really rate your looks with a number in the first place?