Glendale is full of Armenians. Armenians are glamorous, beautiful and curt. I had a garrulous conversation with an Armenian Lyft driver and I asked him why Armenian waitresses always glare at me like they hate me. He said "Armenian women only smile when they really like you! You have to earn a smile from an Armenian woman!" When I said they didn't all give me the stinkeye, he said "you see? You are very popular with Armenian women!"
I've got a Moroccan friend. He's very courteous. When he's around his Moroccan buddies every discussion they have sounds like they're about to kill each other. It took me a while to figure out that when discussing something passionate, you have to be passionate, even if you're all on the same side.
Everybody is friendly in their own way. The Russians I've met are extraordinarily warm and friendly... unless they're talking about other Russians.