Second this. There are a lot of "signatures" in most asm. Programmers for 6502 and derivatives might be a nasty bunch of sadists that love to do weird stuff to save cycles, but even there there are lots and lots of common patterns that often "happened" just because people learned from the same sources, or because it made sense, or because conventions appeared.
I never had a NES, but I had a C64, and the 6502 code wrote there seemed nasty to translate on the surface, with lots and lots of self-modification, for example. But in the end most of the self modification was specific looping patterns because the 6502 can only index 256 values, and so many loops involved writing addresses into the looping code, iterate 256 times, increase the most significant byte directly in the code and see if you'd reached the end, and jump back to iterate 256 times.
Most of this "nasty" stuff is relatively well known by now and much of it is relatively regular and easy to detect.
I never had a NES, but I had a C64, and the 6502 code wrote there seemed nasty to translate on the surface, with lots and lots of self-modification, for example. But in the end most of the self modification was specific looping patterns because the 6502 can only index 256 values, and so many loops involved writing addresses into the looping code, iterate 256 times, increase the most significant byte directly in the code and see if you'd reached the end, and jump back to iterate 256 times.
Most of this "nasty" stuff is relatively well known by now and much of it is relatively regular and easy to detect.