ill share one of my worst moment as a newbie cel 
collector...
   I was very excited to get a certain cel when 
it arrived in my mailbox I found this piece of 
paper with a drawing of the character on it with 
the cel, in fact, it looked exactly like the 
cel. @_@ so I thought it was a mistake and I 
emailed the seller (who will remain nameless) 
and told them that they sent me two things and I 
would be glad to send it back to them, or I 
would pay them for the extra that they sent me. 
In fact I was keen on keeping the extra cause it 
looked like it was used to make the cel.
  the word douga never meant anything to me, and 
this was a private sale...
I think that people like me is the reason sites 
say "with sketch" under the cel. 
^_^
   Turns out that I got to keep the drawing of 
the cel with the compliments of the very bemused 
seller..and she even threw in a tutorial on the 
words douga and genga for absolutely free...
**sigh**
hey this was like three and a half years 
ago..and I still blush..