Most Helpful Guy
Lol it's not shallow if it's something that can be changed. There are hardly any girls who dig mustaches so I don't see why any guys in 2015 would have one. Unless the guy is a complete stud and can attract girls no matter whatever style he rocks. It's only shallow if you don't fancy a person for something they can't control, like their height for example. Personally, I think mustaches are outdated.1
Most Helpful Girl
I think shallowness takes a lot less work that this. LOL When someone is shallow, basing their preference on an appearance - these are usually things that can't be helped if other people didn't fit the format.
For example, if a guy says he only dates thin women, this of course excludes the big girls, so in order for them to be part of his preference they need a lot of time and work to be his type. If the girl says, "I like tall guys," then short guys have no chance whatsoever, this can't be helped. If a girl says, "I don't like moustaches," then the reality is that a guy can shave it off in one minute and then that's that, he has potential to be her type again. :)1