Most people are very good at discovering character flaws and faults in others; in fact, it seems to come naturally, whereas, for ourselves, significantly too often, we give ourselves either a free pass or the benefit of the doubt. This type of inconsistency, in which we are quick to see that others have feet of clay but we, ourselves, are relatively speaking, just made of more integrity, is good for assuaging our own ego, but of little merit in the real world.
It has been said, that in order to really understand another person, you need to walk a mile in their shoes, which is absolutely true, but rather difficult to accomplish. In actual fact, we often don't know where people really come from, what they have had to deal with, what they are really trying to accomplish, and who they really are, so being quick to criticize anybody without knowing their circumstances and their story, is probably the wrong attitude to take under most circumstances as criticism rather than being something that betters the other party, is often taken as a reprimand that they are inferior, and in particular, inferior to you.
A far more effective attitude to take, is one of helpfulness to others, so that, if in your perception you ascertain that someone is doing something wrong or inefficiently, show them considerately the error of their ways, or at least the possibility that they could look at things differently or do things differently, that perhaps has not previously occurred to them, that is to say, try to be of help, rather than an overbearing annoyance.
So too, people need to the best of their ability, step outside of themselves, and recognize, that if they don't particularly care to be criticized, especially by those that they believe really don't know what they are talking about, or by those that may indeed have a valid point, but make sure that their criticism is especially deep and cutting, need to recognize that if the heat in the kitchen is too much for them, than they should not want to treat others in the same manner.
We are all imperfect human beings, all in need of character improvement, personality improvement, and the like, so that, many are quite forgiving or forgetful of their own faults, but take a certain kind of perverse pleasure in pointing out the errors of other people's faults, perhaps in the mistaken belief, that they are being helpful in such criticism, but often this is done with selfish motives akin to the supposition that by lowering another person's image or self esteem, thereby means, that you have, subsequently risen above them.
We can all do much better, by first of all thinking about what we are saying and the real purpose behind it, before we actually say it, as well as taking into account, what is it that we are really trying to achieve, for if our purpose is to essentially knock down a person, that isn't really very constructive, for we have an inherent obligation, rather, to do good unto others, and certainly to live our lives in all aspects that reflect this in practice, by doing the very things that we desire to see done by others.