In what situations can one use 帥哥? I do hear people say that a lot to me in China and I am always surprised by the timings and situations in which people just, kind of bluntly I feel, say this. I wonder what all those situations would be where someone could say that to you and why it's been said so often, it seems prioritized to saying some other, more proper things (I believe) sometimes (as if appearance is the most important thing "to talk about and mention", giving it a lot of priority.)
In my experience, 帥哥 is more addressed to refer to young people. It's like "Hey young man" in English. No matter what, being young is a beauty. People call the young generation 帥哥 in memory of their own long passed golden youth years.