And yeah, Back Bay is sort of a toxic place aside from the crunchier vibe going on around Copley Square and the Public Library... at least during the summer, it is mostly filled w/ Europeans on vacation and is a little less of a gaudy rat race.
Delux is indeed cash-only, but I would just say that it's way too popular and trendy to be classified as a dive. Like, you can't get a table there after 5:45 on any night... but it *is* still small and charming, and they make a killer grilled cheese, and they fill a wine class all the way up for you, so it does meet some criteria. As I said, one of my long-serving go-tos...
Lol, honestly, I like Boston quite a bit. I think the things that irritate me about it the most would apply to any city... and I'm not going anywhere further from "home" than this, so it's my place, for better or for worse. I don't have any real living experience in another city or cities like you do, so you're much better placed to make comparisons/judgments.