Beautiful people attract our attention. There's no disputing that fact. When someone's hot, we're going to want to look. Now it's up to the individual how to react to that bit of sensory input.
You can decide to not want to be a creep, and hold yourself back from staring or making said attractive individual feel uncomfortable. Sadly, a lot of people don't do this and would rather pull one of these and make things super, duper awkward.