Back here I mentioned in passing how one of my constant bugaboos in bad writing is when we get description vs. observation. This was one of those on-the-spot coinages, where I took two words with marginally different shades of meaning and used them to imply two markedly different things.
When you describe something, you're simply looking at it and giving us external details. When you're observing something, you're doing more than looking: you're assessing, comprehending, coming to an understanding about it, and then communicating that understanding. It's the difference between "He was bored" and "He pulled out pocket lint and lined it up on his desk".
Joseph Mitchell was a master of reporting back telling details — not surprising at all, since he was a reporter, y'know. In Joe Gould's Secret, his marvelous book about New York street personality Joe Gould, Mitchell noted many things, but one detail that always stuck with me was something in the man's eating habits. It wasn't just the fact that Joe put ketchup on everything ("It's the only grub that's free", said Joe), but that he would ask for a cup of hot water, add ketchup and maybe pepper to that, and have himself a cup of ersatz tomato soup to go. Such a detail might have slid through another writer's fingers, but Mitchell's eyes and ears picked up on them faithfully.
Because we get description far more often than observation, and because observation's so hard to do reliably well (god knows I don't do it well enough), I try not to come down too hard on other people for tending towards the former. But the latter is always worth fighting that much harder for and sticking around to find.