I think many of us who have heard someone describe crucifixion understand that it was a terrible thing. In Michael Licona’s The Resurrection of Jesus: A New Historiographical Approach he mentions that Cicero commented on crucifixion, so I decided to search for the broader context. It is in Against Verres 2.5.165. He is bemoaning the crucifixion of a Roman citizen named Gavius who cried out over and over that he was a Roman while being lead to his death. One Verres ignored the claim and proceeded anyways.
In his accusation against Verres he says, “You confess that he did cry out that he was a Roman citizen; but that the name of citizenship did not avail with you even as much as to cause the least hesitation in your mind, or even any brief respite from a most cruel and ignominious punishment.”
For Cicero a Roman citizen should never, ever be subject to crucifixion. It is “a most cruel and ignominious punishment”.
On the other hand, a Jewish criminal who may be an enemy of the State has no rights. When Jesus went to die he went to suffer “a most cruel and ignominious punishment”. It was troubling enough of an event that Cicero couldn’t imagine a Roman being allowed to experience it.