Not the GP, but when I take strolls through some open source project hosted on GitHub, usually I am not impressed either. Unnecessary OOPism, way too long procedures, that instead could be pure functions, badly named variables, and way, way, waaay too many willy-nilly added dependencies. If that is what the LLMs mostly learn from, I am not surprised at all. But then again this stuff was also written by humans. I remember one especially bad case of a procedure in a very popular project (in its niche) that was basically a 1 man show. A procedure of 300+ lines doing all kinds of stuff, changing the global state of that service it is implementing. But that code was or is relied upon by tech giants and other businesses and no one improves it. They are happy with paying that one guy probably not so much money.

If only more engineers admitted, that something they wrote is not good code, but a product of its time, then I think we would get more realistic expectations.

It's OK to say that something you made is shit. It is OK to say that you were not given time to do xyz.

How you recognize something has been made fitting at least is, when you see it in use without much of a change for some 3 or 4 years and while you are the person maintaining it, you rarely ever need to touch it, because you built it in a way that is simple enough to not have tons of bugs yet flexible enough, to cover use-cases and anticipated use-cases.