A survey of women reveals that they are overwhelmingly confident of their ability to detect even the slyest of male glances at their breasts.
When 847 Japanese women were asked “can you spot it when men glance at you?”, 58.3% answered that yes, they could spot furtive glances at their breasts, as opposed to 41.7% feeling unable to detect such attention.
A sampling of their responses:

M-Men are looking at me like that!?
I can completely tell the direction of their gaze.
“Ah! You were checking it out” – I pick up on this.
I really pick up on those creepy glances.
I’m not sure I spot it all, but I often see it.
There are a lot of guys who try to glance but end up looking with their whole face.
I notice it a lot when sat on the train. It’s really obvious.
If they’re not totally ogling you it’s quite charming. My guard’s up though.
I’m quite nervous so I notice it quickly when they do that.
I like clothing which shows off my cleavage so I don’t care.
My chest is nothing to speak of so I don’t get much attention.
I always pick up on it when the men I’m with are checking out other girls.
I’m actually the one checking out men’s nether regions – I wonder if they notice?

I really lol-ed at some of the comments that the users posted regarding this topic