> I mean, I get it, these aren’t places foreigners should be going, but their forbidden nature always raises eyebrows.

Snack bars aren't anything forbidden or erotic, they're bars where women are employed to speak to the customers and entertain them (again, not in an erotic way), that's it. I live in a suburb with lots of them around, it's not some kind of red light district filled with brothels, they're just bars I pass that usually have badly sung karaoke blasting out.

I also don't understand the replies you're getting as they seem to have run with this misconception, I can't be sure these people have even visited Japan!