I should make the distinction that there are many subtle levels for men to react positively to me... the least offensive just admiring, and the worst what I would call oggling.
A man flirting is nice. I'm usually flattered. Looking me up & down then smiling makes me feel like I'm on display, but if he does it in a nice way I don't mind. Yes, there's a good way & a bad way.
There's what I call the "turn-around". I'm sitting on a bench, a guy is walking up behind me and he waits until he's 15 or 20 feet beyond me, then turns around and looks, as if I'm not going to notice it. But, I did the same thing as a guy, so I can't knock them for trying.
As a guy I had friends that would oggle women, some even stooping low enough to call out to them in public, or honk their car horns to women crossing the street in front of them. Now that I'm a girl, when men do it to me its just annoying as it always was, and just as degrading as I always imagined it to be. It seems to come in spurts. Some days I don't have one man even look at me. And some days I'll have a dozen different men doing everything from honking their car horns, to making kissy noises at me and talking dirty to me while I walk by. One word... disgusting! And no, when I'm oggled I'm not neccesarily dressed provocatively. Sometimes its just jeans & a t-shirt.
Every girl I've talked to about this says the same thing, "Get used to it." They all say they and their girlfreinds hate summer because it brings all the weirdos out. I suppose we could all dress like nuns, but we can't let people dictate the way we live our lives. Basically, if I decide to wear a miniskirt or a tank top or halter top, I'm prepared to be looked at, checked out, oggled, degraded, & everything else in-between.