Sir, what's wrong with using the word "sir"?
Well, for the most part I don't know if I'm talking to a 20 or a 60 year old. Also, I'm not 15 years old.
And of course, the "sir" and "dear sir" gets a bad rep online. For some people it may be a bit of a red flag.
It's not necessary. If you want me to sir your butthole, got get someone else to sir it
With all duuuuue respect