If you haven't seen it yet, this is a good piece breaking down why it's not just a compliment.

Obviously it's preaching to the choir around here, but I tossed it up on my FB because APPARENTLY not all of my friends are quite so aware.

To anchor this more concretely, consider the behavior of the men in the video. Take a look at how they seek the woman out to wish her a good morning, despite her not having made eye contact or shown any interest in talking to them. Take a look at how they're not wishing a good morning to any other person, particularly male people, also walking around. The woman is walking directly behind the man filming her (the camera is hidden in his backpack), and not one of the men shown in the video are seen to be greeting him and wishing him a good day. Just her.

Why is this?

It's because they don't care, really whether she has a good day or not. What they care about is letting her know that they have noticed her — her hair, her face, her body, her outfit. They want her to notice that they've noticed, and they want her to notice them, however fleetingly.