How to detect if it has a comment

I am wanting to create a rule that is automatically filing things away unless it has a spotlight comment but not a specific comment.
I can get it to file stuff away happily but don't know how to tell it to ignore the file if there is a comment present. If this is not possible it would be nice if in the filter where you select comment then contains you could have an option that says anything.
So the filter would read - comment contains comment perhaps there is a way at the moment but I don't see it.
Thanks
Craig
I can get it to file stuff away happily but don't know how to tell it to ignore the file if there is a comment present. If this is not possible it would be nice if in the filter where you select comment then contains you could have an option that says anything.
So the filter would read - comment contains comment perhaps there is a way at the moment but I don't see it.
Thanks
Craig