Hershey's contains butyric acid, which is the smell of vomit.
My colleagues bring something sweet back whenever they travel, and it's usually gone by the end of the day. The Hershey's was the only thing still left a week later -- even the salty liquorice was eaten!
Yes, Hershey's chocolate tastes bad, however seeing as all dairy contains butyric acid and thus all milk chocolate: maybe lets not go around trying to draw an equivalence between Hershey's and vomit.
An industrial chemist giving a public lecture on chocolate production at a UK University informed that the issue was that milk would go bad due to getting hot whilst collected and poor ongoing refrigeration. Thus Hershey was made with spoilt milk, and tasted as it does. When they were able to fix it there was opposition from the customers as they'd grown accustomed to the taste (of spoilt milk). They thus added the flavour back in artificially, and so we have it.
The lecturers handed out a samples bag at the start with all sorts of samples (including new unreleased confections) - they were like "and this is American chocolate" followed closely by wretching and heaving sounds from across the auditorium, we were not warned! Very memorable.
So that is why, according to a production chemist working in chocolate c.1996.
I dare say they don't publicise the origins of the flavour.
haha, well it's quite possible: stranger things have happened.
I doubt it's verifiable but it seems reasonable. It's possible that it's lipolyized to stop it from spoiling so fast (as it would) and that could start that kind of story.
They also used to add various oil-based emulsifiers that European chocolate doesn't - which is why it has a much more greasy texture.
