So yeah, currently zombies are coded to drop clothing 100% of the time; I’ve brought this issue up as a bug, but it’s one of those “Feature, not bug” things.
Unfortunately, it’s really, really time-consuming to sort through all these useless clothes to salvage something useful. That being said, zombie clothes are very useful in the early game for sources of sewing fodder and for layering.
In that case, I suggest that zombies only drop clothing upon being butchered. Alternatively, zombies drop more rags/leather/whatever and fewer usable clothes as time passes.
Maybe add a third option for stripping zombie corpses?