Remembering that line always makes me laugh. I truly have no idea Folk in terms of their interest. I'm guessing it was opportunistic. If their willingness to dine out with me was based on sexual attraction it was kept under wraps. I only have that two-way frisson with one male friend and we both know it's there and have acted on it 
I do see signals and I do flirt a lot if I'm interested (but never in a professional context). Stiffy man was someone I met at business school and we work in the same field. He was brilliant through my divorce and even offered to lend me money if XH had left me short (he hadn't) and when he said that I just thought he was a true friend.
My Mum used to snort in a cynical fashion and tell me to watch out when I'd talk about meeting these men for dinner. She's always said men and women can't be friends - I just thought she was wrong and old fashioned now I think that she was probably hit upon by friends' husbands and work colleagues. She was a bit of a looker in her day and she's not too shabby now, in her 80s.