Well, it depends.
Sometimes, there is nothing else to look at, so naturally,
people will look at a human being....
For example when someone is waiting...
Sitting....
Nothing to do....and there is not much happening in the
surroundings.....
So if a person walks by, naturally, the attention would be
distracted / would be set on that person.
So sometimes it is natural and it doesnt have any extra
meaning.
Anyways, for me personally I do not have the habit of looking at
girls....because I am shy and I am afraid of getting caught.