In my case the main premise of this thread is not really relevant. The first time I had anal sex, mid 70's, it wasn't called "bareback sex", it was just "sex". The topic of safe-sex was never discussed. Also, this Top/Bottom dichotomy was not prevalent as its now and it was not common to bump into a "slutty bottom", as it is the case today.
I had met Ron, a gay guy who was very open about his need for sleaze and it was through his stories and sexual adventures that I discovered that although I did not identify as gay I liked the way in which men have sex (impersonal, anonymous, no-strings-attached, dark rooms, etc) compared to the way women expect men to behave sexually. It's not that when it comes to sex I prefer men to women, but that I prefer the way men engage in sex. It's like if I were a professional Baseball player I doubt a softball game would be very exciting to me.
Ron had told me about the YMCA in New York City and that it was cheap accommodation when visiting the city. He had also warned me trhat some guys look for sex but nobody is pushy. I found that exciting and decided I wanted to have sex with guys so one day I took a bus to NYC and arrived at the West Side YMCA and took a room in one of the men's floors, maybe 10 to 12, or something like that. I was 23, very masculine and in good shape
I was lucky that my room was right in front of really slutty guy in his 30's who would leave his door open and had many guys come into his room. I could hear the moaning when the visitors were shooting their loads. At one point he signaled me to come over and fuck him. I went just to play with his hole and it was a tremendous turn-on when I felt his cummy hole. I wanted my own hole cummy!
I stayed for several nights and decided to be the cumhole of the floor, something not common those days. The following night the guy across the hall was gone so I decided to leave my door open and lay on my bed, dimmed light. I let guys into my room all night until about 4am, too tired jerked off and went to sleep. I estimated that I had taken about 15 loads that first night. The fun stopped when "AIDS" or "Gay Cancer" was first announced and everybody panicked, including me.
First bareback, planned or unplanned? None.