It's a bikini top. The grab not nice. Looking should be expected and I love it when I'm at the beach/mall or grocery store if I just going in shorts and bikini top.
Grabbing I wouldn't do... Without (verbal) invitation that is.
But I have seen women walking down the street dressed like sluts who give me bad looks for staring.
One time a gal was real dolled up emo style, she was walking ahead of me, she went up the stairs, then she just stopped and turned around and gave me evil look. I was barely looking.
Dumb shit, looking back I wish I'd thrown the hypocrite down the stairs...
Bottom line, if you dress like a slut, you'll be stared at.