And remember: "It's a cultural difference" is NOT the end of a conversation. It's the BEGINNING of a conversation. After saying "It's a cultural difference," it's important to articulate that difference, and how my expectations are different than your expectations, so that we can be understanding and flexible towards each other in the future.
Using "cultural differences" can be a cop-out to avoid responsibility for unacceptable behavior which I, or someone else, is unwilling or unable to actually justify. Any time somebody starts saying "cultural difference," watch carefully, to see if that same person is trying to get away with something, or to figure out what topic they're avoiding.
That is, if you want to have a genuine relationship with said person. Otherwise, "it's a cultural difference" end of conversation, can be the sound of a door closing in someone's mind.
Anyway, to revisit a series I put a lot of work into this spring, go check it out.
Table of contents for the series
Part one of "How to make friends with a foreigner"
Part one of "How to be friends with a Korean"
Most of the advice is basic, "Don't be an inconsiderate jerk" stuff... but sometimes naming specifics is helpful.