It falls into the realm of something is intimate or not, and the tone of the compliment.
For example, I am super into high heels and fancy hats, especially vintage hats. I get tons of compliments on my shoes and hats from men and women both. Most of the time I accept the compliments with a smile and a thank you. "oh, I love those shoes!" "That hat is really cool" "Those are some great shoes". Etc... However, strange creepy man saying saying in a lascivious "Mmmmm, girl, you are working those shoes" gets a nasty look from me. Similarly, I will compliment another woman if she has a hat/handbag/shoes/coat that I admire.
I also get complimented a lot on my smile, I always graciously say thank you because I see that as a genuine sincere compliment without any undertones. Even if it is an opening line, it's an opening line that shows me respect.
Compliments on my physical appearance, it depends. BF can compliment any part of me in any tone (he does save certain compliments for alone time for the record), because we have an intimate relationship
. My girl friends and my close guy friends can give me similar compliments, because we have trust built between us and I know it's just a compliment, not an attempt to get something more from me. Not okay for random strangers to say that because I don't know what their intentions are, and 99% pf the time, those intentions are sleazy.
Like most gray areas in life it boils down to, know your audience, mind your tone and be sincere.
Cute side story. One evening I popped into the little corner store in my neighborhood after work. I had on one of my fancy hats, high heel boots, pencil skirt, I had worn to work. This little girl yelled "Oh my Gosh Mommy, look at that lady, she's so pretty". Those compliments, always welcome!
Yes, I smiled and thanked her.