Yelling brings you down to their level, which is what they want.

Dismissiveness shouldnt be tolerated. Get your spouse on board that you are a united team. That you will be respected as an adult that pays for him. If your partner is not on board with that, then you must disengage. "Oh you want a car? Not my problem. Oh you need my help with something? Oh you should have thought of that when you disrespected me."

You can love them from a distance. But yelling only brings you down to that lower vibration level. I know, as I have been there.

Yeah, never yell. 

I basically keep my mouth shut and offer no opinion - just let DH deal with it.  And he haaaaates being dismissed. So much so that he'll stop helping YSD as well. She's actually walked away from him several times while he's trying to help or answer a quesion she asked. Presumably because she didn't like the answer.

If she DOES dismiss me directly, then I simply tell her "And how old are you? How much experience do you have with this thing?" Usually this makes her go, "Oh, yeah, ok." But if she's still dismissive, then I just say "Good luck figuring it out yourself then."

I have permanently dismissed OSD. I have learned my lesson. Instead of her asking me a question and as soon as a give the answer, she responds by telling me I am wrong and don't know what I am talking about.   I just say" I don't know ask your father."  Because it doesn't matter what I say unless it's the answer she wants to hear, she really doesn't want to hear it. So why waste my breath.

I'm with Clove. DH needs to come down hard with respect for his spouse. Anything he wanted from me for the next month would be,  "I don't do things for people who are disrespectful and dismissive." Hell, he'd be lucky if I passed him the ketchup.

It really depends on what the dismissive attitude was for..... was he dismissive of some "unsolicited advice".. or was it in response to a reasonable request to clean up his room or do an assigned chore.

It's not unusal for teens to have times where they don't want to hear our input... remember... they know it all at that age..lol.  Sometimes.. as well meaning as our advice may be.. they will need to learn some lessons for themselves.  But, people in a household should show respect for one another.. and that also means that he should be called (not yelled necessarily) on his attitude when it crosses over to rude..

But... it is a two way street.  If the kid likes anime and an adult is putting it down... maybe you will see a dismissive attitude because we are talking about an opinion... where the child doesn't necessarily need to agree with the adult.. and the adult needs to let the child have their own interests (within reason.. legal etc..).

And... the "I put a roof over your head.. my way or the highway" perspective of an adult may actually bring more attitude too.  He didn't ask you to be the breadwinner... It's his own parent's responsibility to raise him.. and if they are incapable.. that doesn't mean he has to suck up to you.. just because you are paying his parent's obligations.  It's a fine line here.. but you are doing his parent's a favor really.  Of course everyone should show some gratitude when someone does somethign nice for them.. but don't expect a whole lot when you are providing basic human needs that his parents should be otherwise producing for him.  I didn't feel particular gratefulness to my parents for raising me... i think kids sort of expect that is the parent's "job" to do that... but of course.. when I got a treat/gift.. I knew to say thanks etc..  But that didn't mean that I didn't at times act like a turd to my parents...