Topical-sketch writing were incredibly rational and well reasoned: don't do a joke if the subject doesn't deserve it. An ad hominem attack on someone might get you a cheap laugh, but it doesn't earn you any long-term trust. The biggest rule was: you attack whoever's in power. Don't bring your personal bias to the table.
My main qualm about TV criticism has been when people review TV the way they review movies. They watch the pilot, and write a definitive review of the show. The obvious analogy is that you don't read the first eight pages of a book and then talk about whether the book works or not. People want so desperately in this day and age to declare something thumbs-up or thumbs-down that they declare it immediately.
It's so much easier to write for an actor than for an imaginary character and then try to fit that character to an actor. It doesn't work very often in my experience.
