Why? :( You wouldn't want Sandy to be naked? I'm talking nothing visible ignore the fact that she's a girl (because she's a freaking squirrel) real-type squirrelly, nothing there at all squirrel. Male characters like SpongeBob being naked and just having nothing there is fine, but there seems to be a double standard with girls even though they're both animals. Although to be fair, she is seen with a bra in the show normally so maybe that would make it a little awkward even if there is nothing.
By the way, this was what Robert Ryan Cory intended her to look like, but it was turned down for being too gross/off-model/funny:
Skinless Sandy by
robertryancory, on Flickr
The episode would have gotten at least a 9/10 if she looked like that because it would have added visual humor. :P