That's not always the case though.
My wife is down to a DD cup now (was DDD, but she's lost some weight). She wears bras that minimize her size as much as possible and never wears low cut shirts except around me, but guys stare at her chest all the time. As a matter of fact, one guy that she was helping at one of her jobs never looked up from her chest.
Now the women you describe that wear the hot pants and booty shorts and stuff, they just want certain attention and need to get over themselves.
So the moral to my story would be that if they are doing their best to not draw attention to themselves, but still are pretty or have a large chest or whatnot, it's best to be sensitive to their feelings. But if they are letting the sweater puppies out on the porch then they shouldn't complain when someone calls them out on it.