If a friend is often in a state of anger, think of them as “he might be angry” instead of “he is an angry young man”.
If your landlord calls you at unusual times, instead of thinking of him as “a lonely soul expressing his loneliness through venting” think of him as “he might be feeling lonely when he vented out at me”.
If a colleague does not radiate positive vibes, instead of thinking “she is a negative person” think “she might be going through something in her life.”
Of course, do all the right things you can to deal with it.
Please know, though, that moods of human beings are moving entities. When we label them as angry, frustrated, negative–we put them in a box. We wouldn’t like to be put into one during our worst times. Why cage others then?