My Marius has those "cotton balls" too. I was thinking the same thing about having them completely removed because you can't see any remnants on my parent's male cat Socks, but I guess that's because my Marius got a different neuter procedure??
Ok, I have to add to these silly stories. My family's family dog, Misty (rainbow bridge) had a tendency to 'mount' the neutered male cat Socks every now and then, and my parents would get all disturbed and discourage that behavior. I just thought it wierd because Misty was FEMALE!!???!!! LOL LOL It was especially embarassing when guests were over...poor Socks would just try to slink away!