there certainly is a difference in texture of the coat and the general smell of a neutered male vs an unaltered one. the 2 males i have i had neutered for a couple reasons, 1) i'm allregic to the smell of the buck greese (so for me getting them not to smell was important) and 2) because i wanted them to go in with my girls.
now, do they stick one way or the other greatly depends on what they get into and how lazy they are. on hot days no one really wants to move much so the litter training goes out and the window and they'll pee whereever theywant and lay in it. mind you the females do that too and it doesn't always depend on the temperature but i have noticed they do it more when its hot out.
because of the buck grease they do have a stronger general aroma then females but it doesn't smell that bad. just kinda like the air in a stuffy attic or closed chest, old and a bit musty. its not a bad smell, just a different one.
and there are health benefits to be had with a neutered male. not nearly as many as a spayed female but there are benefits there none the less. it does reduce risk of certain cancers (not as many as females though) but it can also prolong the life expectancy by 1-7nish months. without those hormones causing havic with them mentally and making them big all that physically their body tends to have an easier time of dealing with aging. more resources can be directed to other things.
also, there is a general temperment difference to be expected even in rats that were not aggressive to begin with. i was actually surprised by this myself. when i had stewart neutered i was not expecting any change in his personaility as he was past 1.5 years old and he was a pretty laid bakc little man as it was. but after the neuter he's acting like a little fuzzlet. he's hand wrestling with me (something he NEVER did or showed even the remotest interest in doing). and he's even more of cuddlier then before. i had had him for a while before the neuter so i can't claim that he just got more used to me, he had already accepted me. but now he's vying for position of the biggest sook right alongside sookie and violet. and its a close call, i'm not sure which will win out in the end.