Avajoy, with my first two cats, Sydney and Charlie, I took them to be neutered and I thought their "cotton balls" (lol!) looked smaller after the procedure.
Elvis and Danny were both already neutered when I adopted them, so I don't know what they looked like before. I guess they look kind of small, like with the first cats, but again, I wasn't sure so I decided to contact the lady from the shelter and ask her if she was sure that Elvis had been neutered.