What the seller means is that the trace-lines
(the black outlines) have all faded.  Yes, the
cel looks like that (it's not the scanner) if
there are no trace-lines.

Trace-lines can fade away (with time) if the
cel is improperly stored or exposed to harsh
light (flourescent, direct sunlight, etc)...
the original owner (a gallery or studio, etc)
probably didn't realize how fragile the lines
are, which is probably why the cel is in that
condition...

Lady Z