Ask HN: Do you criticize?

If you follow HN, Reddit and various programming-related sites, you may have noticed that much of their content is criticism of some software, people who developed it, the design decisions they made and so on.

Programmers are prone to criticizing and tactlessness. Torvalds and de Raadt are perhaps among the better known examples. I too often find flaws everywhere (not just software) and criticize.

Lately, I've been reading Dale Carnegie's classic, whose fundamental principle is "Thou shalt not criticize", and came to the realization that the criticism I dished out over the years, however deserved it may have been, has hurt my professional relations, and my career would have been much better off if I had reserved ALL the criticism of others' work.

I made it my New Year's resolution to stop criticizing, but the habit of doing this is so deep, it's like a drug.

Do you criticize, and if not, how do you manage not to? How do you deal with coworkers doing/saying stupid things, especially in programming and science?