Checking a woman out? A-OK.
Leering at her until she feels like she needs to call the cops? Not so much.
It can be a thin line, so if you don't know where that line is, probably best if you don't do more than a cursory glance.
If she's showing them off, take a good look, don't mind if she notices, and move on.
If women have nice boobs, we put them out but try not to stare so long it seems like you have xray vision. Nothing says perv like a ten second stare.
I'll try not to stare at your boobs for more than nine seconds at a time. :wink: