I did this once, for the most notorious, infamous sperm bank of all. They needed an O negative donor with blonde hair (it was blonde then) and blue eyes.
Ah, the questionnaire: it was over twenty pages long! Yes, they asked me if I was gay. They gave me mathematical problems to solve, to demonstrate mathematical ability. I had to submit samples of my drawing and painting, to verify "artistic talent." I had to take them into Tupper and Reed, a music shop in Berkeley and play a piano there to demonstrate my "musical talent" (the Brahms Rhapsody in B Minor was enough to convince them). They poked me and prodded me, measured my body fat and then felt me up again. I had to take a color vision test and, of all things, a Rorschach ("Uh, it looks like a bat!"). They also took my blood pressure, right on the spot. The only thing I did not have to do was compose Alexandrine verses in my head while unicycling down University Avenue. And no, I cannot ride a unicycle. They said they would be in touch.
So, what did I do? I was prohibited from "donating elsewhere" for three days. I went to the Flamingo Motel in Berkeley and masturbated into a cup. The person sent to collect this gathered it in a syringe, remarked on the quantity and its appearance, then mixed it with egg white and some other material, and injected it into straws (mine were gray straws with red marks on them) and I became donor #28. I made well over two hundred straws of semen. For that, they paid for the motel room: $31.00.
I know only about one recipient, for whom they needed the O negative donor...a (then) 42 year old superior court judge in Chicago. I know she got some of the juice and I know she was inseminated with it on more than one occasion. I do not believe any offspring resulted, from her or any other recipients.
Now I am too old to go that route and I do not need any ego reinforcements of that kind as I did twenty-five years ago.