This is just my own personal opinion and taste 
but I hate cels without sketches. I would 
probably sell cels too just because its missing a 
sketch. And I think it sucks when a cel is 
seperated from its sketch and its highly unlikely 
they will get to reunite over time, thus is why 
as much as i love some of my sketches, when i 
decide to sell a cel, it goes with it. 

what I dislike more is when i see a seller 
selling the sketch and the cel seperately just to 
make that little extra profit. I know its their 
right or whatever but to me, it just aint right 
>__<