There is a function called IsHairProp() ( only works with hr2 (prop) hair ) I never found it to be reliable.

You could check it's name or actor names and / materials for certain things.
sadly because there is no recognised naming convention, most modellers
use a variety of names. so searching for cap or skull in actors / materials
may not work, and as you noted searching for "hair" in the name may also not work.

Seemingly, no 2 people use the same naming convention.
Some modellers don't even use the same conventions for all of their models.

*edit*

you could check it's parent or what it is conformed to.:

For figures, check the conform target :

    if figure.ParentActor().Name() == "Head": for props check the parent:
    if actor.Parent().Name() == "Head":

if the parent / conform target is "Head", it is likely ( not 100% foolproof ) that it is hair. 
( make something foolproof, they will make a better fool.)

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