The most incredulous reaction was also the most disheartening to me. I went to donate blood right after 9/11, walking in with my black leather Harley jacket, riding boots, and carrying my motorcycle helmet. I guess to the screener that made me look straight, though another gay probably would have seen my look as being more Tom of Finland.
The screener was quickly going through his long list of verbal questions about diseases and other personal history, my answers all no's until he got to "Are you homosexual?"
"Yes." He shot me a surprised look, and paused awkwardly.
"Let me ask that question again. Are - you - a - homo - sexual?"
"Perhaps you don't understand the word. Homosexual means a man who has sex with other men."
"Yes, I'm a homosexual, I have sex with other men."
He entered my response into his computer, and told me I was barred for life from donating blood, and it couldn't be appealed. I was naive, thought I actually had to have a disease to be banned, and I'd never had an STD in my life, still haven't to this day.
But just being gay in the US earns you the presumption of being HIV positive. I would have lied if I'd known the consequences, as I'm sure many gays do, invalidating this self-reporting question as a means of protecting the blood supply, which it doesn't do. That was the first and only time in my life I felt ashamed to be gay, leaving there feeling rather dirty.