"And if you insist on continuing to make assumptions about my character, I'll advise you only this: assume you will always be wrong."
Every one of us has been the unwelcome recipient of assumptions made by others that were false. Yet ironically we do it to others as well. Unfortunately, assumptions are usually wrong, especially when it comes to motives behind actions that we find objectionable or things others have told us about another individual. And because they are often wrong, our view of others is often misguided and also wrong. I would suggest the following practices when it comes to assumptions made about others.
First, before we assume, we ought to ask the individual involved. It is enlightening to have a first hand conversation rather than to make assumptions (that are usually wrong to some degree or another). There is nothing wrong with asking and it might save us a relationship if we do.
Second, be wary of second hand information. All of us have a grid through which we see others and if the grid is wrong we will pass along untrue information or perceptions. And, where there is rancor involved, others have a vested interest in painting the worst possible picture rather than objective information. It is also true that the one passing it along does not have all the information themselves. It is amazing how much more quickly we grab onto negative information about another individual than we do positive information. It is our fallen nature.
Third. if you don't have all the information think grey. Understand that there is usually more than one side to a story and knowing that you don't have all the facts resist drawing rigid conclusions. Things are not always what we think they are. We ought to be circumspect in our thinking and comments.
Fourth, if you don't need to, don't share negative information about others. Scripture calls this gossip. Bad news spreads quickly and to the extent that we fan the flame we are guilty of gossip. And, if we don't have all the facts we may be guilty of worse - reputation assassination.
My assumption is that we would want others to practice these principles with us. Let's therefore practice it with others.