Well, If it were just one person doing it, It'd be hard not to look. It's an oddity, It's an oddity featuring something I enjoy looking at. Not looking would be a sin.
The appeal would definitely wear off if it became common enough though. It probably wouldn't take many women to go topless every day for a summer. I bet at the end of the summer all the odd looks from locals would disappear. Someone should organize that to see if my theory is correct...