I think it’s a girl thing. In my experiences with straight women, it’s a psychological trauma because saying you need an STD test means you’re slutty; it’s a moral judgment. Nice girls don’t sleep around, and STDs only happen to slutty, bad, dirty people. You might be surprised at how many straight women think this way.
I have seen this attitude even in promiscuous women who do not practice safe sex and are currently symptomatic. My sister’s friend N recently went around asking all her friends for advice because it was “itching, stinging, and burning down there.” She admitted to at least a dozen sex partners in the previous few months, most of whom she barely knew, and she rarely used condoms. No one would tell her “get an STD test” because it was mean. At my urging, my sister finally suggested it to her, and N had a hissy fit, because that meant Sis was calling her a dirty slut. This despite the fact that N freely discusses her sexual escapades and has no moral problem with casual sex.
Sis’s roommate L went to the gyno last month and was pretty much forced to undergo the routine tests that student health does for STDs. She went on and on about how she didn’t want or need them because she only has sex with people she loves. She also sees no need to use condoms with people she loves. Does she think that the love rays will zap the pathogens? No, it’s just so rude to suggest that your One True Love might be “dirty.” Turns out one of L’s True Loves gave her HPV. She’s keeping this a secret from her Current True Love, who does not use condoms, because she’s afraid he will think she’s–you guessed it–dirty and slutty.
Even some of my married friends who know they don’t have STDs (well, are 99% sure) get indignant when mandatory testing is performed when they go to renew their prescriptions for the Pill. When I say, “What’s the big deal? It’s the law where you live–everyone gets tested!”, they say, “Well, you know, it’s just so ridiculous and degrading…to think I might have an STD–crazy!” Even though they should know it’s not personal, they feel judged.
My guess is that in the queer community, most people have been able to escape or avoid this kind of programming.