The song challenges the people who claim not to like certain music because they don't think they should like it, but secretly enjoy listening to it (hence "don't pretend you hate us when you sing along"). I like the lyrics, because it's true, there are so many people who do just that, and now they know we're on to them xd
When it says "we all look the same in the dark" I think it's saying that on the radio it's just the music you hear and that's what you should judge them on. Liking them on the radio is the real test, since you're not influenced by knowing who the band is or what they look like, etc.