That something 'special' quality is probably what 
is most important to me. Its hard to describe, 
but I'll give it a try. 

Sometimes there's a certain moment, or a certain 
look that when you see the cel you just know 
you'd want to frame it and put it up on your 
wall. Even if you never get around to it, it is 
that special quality that makes it art. It can be 
anything from a portrait, a lovely composition, a 
special scene, or just an expression. But somehow 
it leads to the same feeling of: "Damn. I need to 
hang that on my wall."

When a cel makes me say that to myself, I know 
its one that I want to buy. There are a lot of 
beautiful cels out there, but if I don't feel the 
urge to hang it on my wall, more likely then not 
I'll pass on it. I find its a pretty good rule to 
follow.