Where do you draw the line?
At the personal boundaries of the one being asked, which is why 'not being creepy' is more or less an equivalent statement to 'respect the boundaries of other people'
The thing is, just because someone pays you a compliment it doesn't mean you owe them anything.
Unfortunately, it is the people paying the compliments that most often need this explained to them, because one of my major peeves regarding random compliments is the person giving the compliment then feels I owe them A) my attention, B) my custom, C) my phone number, or sometimes so far as D) my body.
He'd just wind up in the friend zone or worse 'harmless friend zone'. A good way to make it clear, is in fact, to pay compliments in the first place.
In my experience, guys who talk about the 'friend zone' as a bad thing are much, much more likely to ultimately be creeps with a misogynistic sense of entitlement towards women.
Honestly, if someone has a serious problem with the idea of being friends with a particular woman, they aren't looking for a romantic relationship
with that woman, they are looking for a sexual relationship
with that woman, a vastly different kettle of fish.
Romeo saying to Juliet upon meeting her "If I profane with my unworthiest hand. This holy shrine, the gentle fine is this. My lips, two blushing pilgrims, ready stand
to smooth that rough touch with a tender kiss!" would have to be changed to "I see you're a fan of Star Wars. Do you want to go to a convention with me next week?"
This one is entering her teens,
Ripe for sentimental scenes,
Has picked a gangling unripe male,
Sees herself in a bridal veil,
Presses lips and tosses head,
Declares she's not too young to wed,
Informs you pertly you forget
Romeo and Juliet.
Do not argue, do not shout;
Remind her how that one turned out.