There's a saying in improv, "Treat your scene partner like a creative genius, and you'll give them space to become that."
The first time I heard this, it got me in the core. It's so true: if you believe that someone is unfunny, it will show up in how you play with them. It will effect how you interact with them, which effects the quality of the scene work, which effects whether or not you had a good show, which effects how strong of an improviser you find the people in your ensemble.
Treating your scene partner like a creative genius can be a self fulfilling prophecy... it at least makes room for it!
The same is true off stage - if you treat someone like they're incompetent, lazy, ignorant, selfish, etc... that is all you've given them space to ever be in front of you.
When we remember that we're looking at a WHOLE PERSON, not just a sample of their worst behavior, we have much more room for possibility.
Instead of labeling, when we confront the whole person with the belief that we are more similar than dissimilar, we open up a world where beauty, love, magic... and productive dialogue can happen.