Stuck douga, shouldn't matter-- the 
collectability of the cel depends on the cel 
itself..ie.. Popular character? Actions of 
character;good pose. Centered? Close up or far 
away? (I prefer low fading but some people don't 
mind it) These of course effect price.
 Some cels have rice paper stuck to the backs. I 
personally don't like anything stuck to the back 
and will go to great pains in removing them but I 
also frame all my cels. (sorry dougas but the 
cels mean more to me)