@theluthier this is something that has bothered me for some time and I think I know what is happening; sometimes when you have a curved surface (which is almost always when applying hair), there are some Hair Particles, that have their Roots below the Surface:
As you can see, that only happens in certain places. And when you make the Hairs really short, some will not reach the Surface.
It took me quite some time to figure this out, but when you Triangulate the Mesh, things become clear:
There were non-planar quads and the Hair position was being calculated on the Triangulated Mesh.
Checking the Hoodie revealed many non-planar quads (I just highlighted a few, but they are everywhere):
My guess is, that that causes the bare patches of fuzz.
Not sure how to resolve that, considering the Multires Modifier...
spikeyxxx You are a genius! Since there's a triangulate modifier, I tested what that would do when placed after the multires, before the particles. The fuzz definitely appears more uniform in the viewport:
The broken quads are mostly a result of the ('newer') Angular method that is now default in the Cloth Sim. Setting it to Linear produces a lot less broken quads (maybe even non, when letting the Sim run long enough).