Usually, I won't ever buy a cel with closed eyes 
unless a character is obviously supposed to be 
sleeping or (like Wong from Psychic Force) never 
has open eyes. But there are exceptions to all 
rules, and like the others here have pointed out: 
It completely depends on character and scene and 
the rarety of either of the above.

Here are some of my favorite closed-eyes cels. . .
Everyone has at least a couple, I'm sure. Top to 
bottom, mine are: Iason from Ai no Kusabi (much 
liked character and very rare to find AND a 
favorite scene - my #1 favorite closed-eyes cel), 
Raphael from Tenshi ni Narumon (like the 
character, love the pose), Vash from Trigun (the 
expression! ^_^), and Botan from the YuYu Hakusho 
Movie (100% for scene).

Why not show this cel you're wondering about? ^_^

Many Sharp Smiles,
--Drac