‘Common sense’ is a the easiest term to bandy around, and it means totally different things from person to person.
For me, it’s common sense that unless a) you have an existing relationship with someone where you’re sure your actions are welcome, or b) you’re in an environment such as a pick-up joint where the default expectation is that heavy flirting is welcome, you shouldn’t do anything directed towards women that you wouldn’t be comfortable if a man did directed at you. I call it the Sven standard.
If you’re at work, would you be OK with Sven from accounts pinching your ass when you bent over to refill the coffee machine? Possibly, if you were good friends with Sven, or maybe if you were into guys and thought he was hot (though even then that does indicate a lack of boundaries at work, unless you’ve indicated interest), but if you’re not into guys, and you don’t really know him, the odds are pretty heavy that you’d think that’s really not OK. Let’s assume you’re not into guys, and your interactions with Sven until this point have been on the level of asking where the photocopier paper is.
Would you like it if Sven told you your butt looks great in those pants?
If Sven just made a vague pass at you? Most non homophobes would consider that OK, even if they weren’t personally that comfortable with it, but they’d damn well expect Sven to take the hint if you weren’t interested. If he was then waiting outside ‘just by chance’ at finishing time, despite you indicating lack of interest, smiling, making ‘accidental’ contact, asking if you fancy getting a drink? OK?
Then he does it again next Friday after you politely said no, because you don’t want to cause drama at work? He’s just flirting!
If you complained to your manager, who told you that maybe you shouldn’t have worn those pants if you didn’t want him to do that, and you should probably be flattered, how would you react?
If you were in a (Gay) bar, then, well, the rules are different, and you expect comments about your body, but there’s a time and a place for jumping to more than expressing an interest without encouragement, and no means no. Simple as that.
(No offence intended towards Svens of the world, it’s just a fun name to type).