I draw the line at painting 'fan cel' under the 
image layers.  It's bad enough when people miss 
my signature when it's put in an incredibly 
obvious place as well as all the 'this is a fan 
cel--it is NOT real' all over the description 
when I sell stuff on ebay.  Not that I sell much 
on ebay anymore, but some people see an image, 
don't really look at it very closely or even pay 
attention to the description, and bid.  Happens 
all the time.  

I'm thinking about using a sharper edged pen to 
do the comment at the top-right corner.  that way 
if you get rid of the ink, you can still see the 
note because it kinda works like a needle 
scratching the slightest bit into the cel when it 
inks so if you erase it there's still a really 
thin line left.

Kitt suggested that I just crop some of the cels 
down, and I think I will if I can get access to a 
paper cutter that is sharp enough to do the job.

If that doesn't work I think I might just put 
restrictions on who I'll use registration-holed 
cels for; like people I've worked with for a 
while, know personally, etc.