I can understand your concern. However fancels, 
no matter how well done, aren't *perfect* for the 
most part. And most fancel artists use other 
materials than production cels (like pens instead 
of xeroxed lines). A legit fancel artist won't 
put bogus numbers on a fancel, and signs the 
fancel (since it's their reproduction). 
 
People (like pretty much everyone in this forum) 
who collect original production cels, are pretty 
aware of what is real and what is not. When it's 
in question we go to eachother for advice. That 
doesn't happen too often because most fancels are 
either labled as so, or just *look* like fancels. 

~Tara