It definitely depends on the relationships I have with the person - if we are well acquainted and have had a discussion - I more than likely find it acceptable - but if we just met - then I would prefer another way of expressing your perception of me .
I have a couple of younger friends who call me Daddy, and I don't mind. I do have an intimate friendship/mentorship with both of them, so it's amusingly appropriate. However, they were both polite enough to make sure I was okay with the moniker. When young men use it as an initial greeting, it puts me off, not because they're calling me old, but because they're implying an intimacy that hasn't been established yet.
That last line is super topical and important.
I have a friend who I have been a mentor to for many years now. His father left him and his mom when he was very young and has only seen his father once since then. He is now in his 20's and from the time I started mentoring him he's called me Dad, papa, daddy or even father. He's a young gay man and sometimes he'll call me daddy in a playful way and other times he's more serious. I don't mind it at all. We've never been intimate with each other but the subject has come up and if he were to call me daddy I don't think I'd mind at all. To me it's a term of internment and I love that he feels open enough to call me that.
I'm thinking most of you are referring to "daddy" as in a young gay man referring to an older gay man. And then there may be 2 of you that are referring to literally someones father lol .. Myself, I am on 2 gay apps. Often a younger guy will call me daddy and if I don't know them I am just a bit... put out by it. If I've established a rapport with a young man and he eventually calls me daddy I'm not AS put out about it. Obviously the ones that piss me off are the few that refer to daddy then ask if I'm generous. To my surprise though very few young guys do that. Most young guys hit me up because they enjoy an older guy who knows what he wants, has lived life and is successful and confident. If I find out they enjoy the role play daddy/son, I'm more into it. IF... a sexual banter back and forth as daddy/son is benefiting both of us then shoot yeah ... go ahead. :) Having said this I'm not real sure which way the OP meant in using the term daddy since he was using the term nudism. No one in a pure nudist environment has called me daddy..its always a sexual connotation for me.