Here's Jimmy 2 months before neutering...
And here he is a year after the op...
I'd hoped the changes wouldn't have been so obvious as he had a non-trim, fine, silky coat. Since the second photo ( which is about 3 years old now) it deteriorated a hell of a lot more, partly through use of the coat king and thinners as both can damage the coat further... eventually it starts to grow back wavey and tufty.
I do think blue roans and some other colours get away with it better though. Also it depends on your reason for wanting to neuter - Jimmy was done because Misty arrived on the scene, so one of them had to be done. He's still basically the same dog, just looks a bit different.