We all have categories, for everything, really. The discussion that follows applies to all art, to food, to lots and lots of things. I'm going to cast in it terms of photographs, though.
We all have preferences in photographs. We like black and white, we don't like HDR, we like saturated colors, and so on. We also have ideas, probably, about what good photographs are, and which photographs are "art" (whatever that is). What all this comes down it is, in the universe of every photograph ever made, we would have a reaction to every photograph and could categorize each photograph in a handful of ways.
We try to summarize these categories in the form of a few sentences, giving rules for determining whether we're going to like a photo, or consider it art, or good, a priori. This is certainly a useful exercise, but if we do it with any rigor we wind up with an apparently endless regress of exceptions and sub-rules. It can get a little frustrating, and it appears complex. If you are me, you start to wonder about "the fractal nature of preferences" or some craziness like that. What's going on here isn't as complex as it looks, though.
Ultimately, the real thing here, the actual description of what we like and do not like, is simple. It is that set of all the photographs in the world, and our reactions to them. For every photograph ever made, we either like it, or not. If you prefer, we like every photograph ever made to a greater or lesser degree. This is real, unambiguous, and clear. It's simple. What it is not is practical. We can't look at every photograph and make a note about how much we like it. And, why would we? This doesn't change the underlying reality, though. It's not fractal, it's not complex. It's simple, but very very big.
So remember, blanket statements like "I don't like pictures with people in them" are just shortcuts and approximations. When you say it, mean it that way. When someone else says something like this, just take it as the approximation. Don't get obnoxious when they mention that they like some photograph that has a person in it. The statement was just a rough approximation to the true thing, the collection of all the photographs the person likes, many of which have no people in them.