a lot of the stigma surrounding sex work in the modern day (that doesn't just boil down to misogyny/gender norms/religion) is based on the fact that selling intimate aspects of one's self places a set value on something that many see as sacred
The fact that most of the times the stigma only clings to the person selling and not the person buying makes me think that this is actually a negligible part of the stigma.
I don't think I do know actually. But here's an attempt at answering this question anyway:
We are usually very quick at relating sickness or even discomfort to the food we ate at the time or slightly before. This is a very valuable trait to avoid food that is unhealthy or even poisonous. But it's only based on correlation, so it can turn us off food that is not actually causing the sickness but we just happened to eat at the time.