I've been with dozens of people on their first trip with acid that I knew was acid. And I've had dozens more experiences with people thinking they were taking acid when it was really 25I or something even worse (if it tastes like something, it's not acid). When I was younger taking any drug anyone could get their hands on, I was usually in the latter camp. And I think very few people are privileged enough to
not be in the latter camp as you don't tend to have much control over the drugs you get. Most normal people might get like one "acid contact" their whole life and they're taking whatever he has to sell them.
If you're in the former camp (taking real acid), I have a truly hard time believing the anecdotes of bad things happening. And I think most anecdotes are actually stories from the latter camp. Just take a small dose and know that you can take the edge off with a beer if you really needed to.
But if you're in the latter camp where you don't even know what you're taking, I'm not particularly surprised if something bad happens.