In his book The Mass Psychology of Fascism, in the last chapter which is titled On Natural Work-Democracy, Wilhelm Reich wrote a very good illustrative story of fair versus unfair criticism.
Here it is briefly: Imagine that an engineer has to repair a large engine that his factory needs by the next day. He's working well into the late evening. One person comes along and just smashes wires to be doing it because his wife nagged him earlier. The next one gives the engineer a pile of nonsense about how he's doing it wrong, tells him he's filthy (from working on the engine), and that he's immoral for abandoning his family that evening. Number two knows nothing about repairing engines. The third one had a hard time with his mother-in-law and spits in the engineer's face. Reich says that they are like highwaymen who disturb honest work. Does that sound familiar? This was written at the beginning of the establishment of the Third Reich in Germany, when a bunch of animal rights activists/ environmentalists took over a more or less democratic country and we know what they did with it.
The next person who comes along is another engineer who rolls up his sleeves and pitches in and helps. He knows the work and in the story he spots a mistake that he helps correct, and is POLITE, something that the activists are quite incapable of being.
Compare this to the kind of personal experiences that either teach a person when it is appropriate to be critical or prove that the would-be critic used his brains first. One example was when I was at a stable and a horse in a small round pipe enclosure without food and water begged me to give him some food. Using my brains and my own experience I realized that the horse was a valuable animal and if he was being "starved" it was for a reason. He might have gotten into the sacked feed and was being treated to prevent laminitis. He might have been due for a visit to the veterinarian and needed to be kept from food and water for a prescribed time. The most important thing to realize was that most likely the owner knew what he was doing and I didn't. The horse looked like he was in very good shape, too.
I've seen dirty houses and yards that had dogs that were reasonably clean, healthy, quite well-fed, and free of fleas and disease. This could be genuinely objectionable but it's a home and they're happy and cared for. On the balance it is still good and if I want better I should be willing to pitch in and help. I have done this before and if I were someone who would cry "cruelty" instead of cleaning Edward Taub's laboratory like I volunteered to do, I don't belong around the animals and I don't belong there because I'm either clueless or malicious. In other words, I should be like the engineer who goes in and helps to the best of his ability. Even if I didn't know much he might need another set of hands, maybe someone to bring in drinks and a snack and so on, but to me someone who helps does so by actually helping. A real helper has to be trustworthy, honest, and polite. He has to serve. He has to be truly tolerant. He has to be respectful.