Yes, why expats with Chinese spouses come across as smug and arrogant, AS A RULE, in your view is indeed a mystery to me as well as you. All I can do is suggest some reasons.

1 - many of them have 'taken on' the bad culture. A Chinese spouse will maximise this to help her Western husband cheat his Chinese employer and other FTs at his workplace by telling him how to 'act' there.
2 - others feel being married to a Chinese is a kind of salvation to shed their western misfit stigma.
3 - still others feel very insecure here in China and need a spouse's help to allow them to survive in many aspects of daily life.
4 - a Chinese spouse treats a foreigner very well indeed, even a rotter of a husband, compared to how a western wife will treat him. She will put up with much more BS including drunkenness etc than a western wife would.
etc etc.

Personally I have met many insincere and sneaky foreigners, barefaced liars and self-serving people among the FTs here over the years, married to Chinese and not. I found some of them to be bigger assholes than the Chinese. Dead simple in my case for having married a Chinese. I needed a wife, and a free reign re my employment. No medicals or release letter BS. Truth be told, I should have been dismissed summarily and prevented from continuing my teaching 'career' in China on 6 separate occasions over the years. However, being below the radar and the bad culture here allowed me to survive, with the help of my illegal employment thanks to my wife, which meant my employers had compromised themselves, and therefore couldn't wield the big stick against me. I am disintersted in high living and being high end. Buying a flat in the backwaters didn't cost me an arm and a leg. Each person to his/her own priorities - that's the crux of the matter.

Anyways, for me, it's all over now re my teaching, and I've no regrets. Thanks for responding.