In the linked question, I asked why President Snow lied to Katniss about the status of District 13 (at least in the movie version) in spite of their agreement not lie to each other.
The consensus there seems to be that President Snow is ruthless and sociopathic and would feel perfectly free to violate the disagreement if it was convenient to him. This brought up a related question, though (and there was some disagreement about this point): was Snow actually sadistic? Did he fundamentally enjoy hurting people (e.g. in the Hunger Games), or did he just hurt people when it was useful to him?
The mere existence of the Hunger Games (as well as his participation in them) seems to suggest that he was sadistic. At a minimum, it seems like a pretty sadistic way of killing people to say the least. With that said, in the movie at least Snow suggested that this was more useful than merely rounding kids up at random and killing them on the spot because it gave people just enough hope to make them easier to control. It also helped keep the Capital entertained. This raises the question: did he genuinely enjoy having the Hunger Games, or did he just do it because it was useful to him?
One significant piece of evidence was when Snow tells Katniss that the Rebels were behind the bombing that killed her sister. He told her that he obviously had no qualms about killing children, but that he had no reason to kill the capital children and he considered the bombing wasteful. The fact that he didn't do it because he considered it wasteful suggests that he wasn't sadistic, just a ruthless sociopath who had a utilitarian view of other people.
That being said, is there any evidence (either from the books or the movies) that Snow is actually sadistic (and not merely ruthless)?