I think GY6 rubs girls the wrong way because his definition of a SB is the classic one. A older man takes care of a pretty girl that he sees potential in and helps her achieve her career/education goals. At least that is the impression I get. I definitely could be wrong.
Some ladies think a SD is a regular client that pays monthly. (Set schedule, agreements on how much time to spend with each other.)
Some ladies think a SD is a boyfriend that gives you an allowance. (No schedule, you want to see each other whenever time allows, you prioritize time with each other over everything except family and work.)
Some ladies’ idea of a SD is somewhere between the two.
Personally, my definition veers more towards the classic definition. I’ve had a wonderful allowance giving partner for over a year, but I only call him my SD because that’s how others understand the relationship. I don’t consider him a SD.