Add a particle system to a character's body
set it to hair
assign it to a vertex group
go into "particle edit mode"
comb the hair
then make any adjustments to the mesh such as adding, or removing vertexes.

then once you leave editmode, you will find that the hair is all over the place.
basically, once you made the characters hair, you cant edit the body's mesh. you can manupulate it by moving polygons, but you cant add or remove anything.
this is a minor thing, so i set it to low priority, but unless its complicated, i think its defenitly something worth fixing.

basically, i've assigned the density to a vertex group, so if i make any changes to anything that is NOT a part of the vertex group, then the hair should not be affected in any way.