The second someone says they like Trump, I dismiss everything they say from then on, and I will have as little to do with them as possible

There's a distillery near me with a reputation for good whisky, but I've met the owner, and he's an idiot, bigoted Trump-loving ignoramus

So I won't buy his booze

The painting is Paar im Gespräch (Couple In Conversation), c. 1885 by Simon Glücklich

We used to call that "flipping the Bozo bit".

https://en.wikipedia.org/wiki/Bozo_bit#Dismissing_a_person_as_not_worth_listening_to

cigarettes (nicotine) is for forgetting all the things that dont matter to focus on the things that do