OK, I guess I'll post more details.
My wife & I have two male Shih Tzu.
I had the older one neutered before I started this thread, and he seems ok with it, as far as I can tell. He still likes to hump other dogs, both female & male (male on male dry humping is normal, right?). When we bought the dogs from a breeder, we actually had to agree to have them neutered when they reached the appropriate age. Stud rights cost extra or something.
Anyways, when I told my dad that we neutered one, with plans to do the other one, he was totally appalled. Whenever I mention the dogs, he berates me over neutering, so I started this thread to get more opinions. We still plan to neuter the younger one in a few weeks, even though I'm still not 100% morally ok with the idea. I just don't want him to knock up some slutty bitch.