The [Correct Filename] user field expression is:
\\GEORGE\Audio\[Media Sub Type]\[Artist]\[Album]\[Name].[File Type]
The [Has Correct Filename] user field expression is:
IsEqual([Filename], [Correct Filename], 1)
The smartlist criteria is:
[Media Type] | is | Audio
[Has Correct Filename] | is | 0
EDIT: I've just noticed that there are some issues with this still, I can see why but I'm not sure how to resolve them. Take the Arctic Monkeys track "R U Mine?" from the album "AM". The [Correct Filename] expression generates:
\\GEORGE\Audio\Music\Arctic Monkeys\AM\R U Mine?.flac
but the actual filename is:
\\GEORGE\Audio\Music\Arctic Monkeys\AM\R U Mine_.flac
Obviously when the rename happens, some magic goes on to convert characters that are invalid in filenames, such as ? to an underscore.