Correction: there should be a wide spectrum. I have not seen evidence of this. I have only seen villain Infernals (who are really not much different than villain Abyssals) and heroic Infernals (who are really not at all different from heroic Solars). Problem.
As always, I have problems with anyone choosing to put anything on their character sheet without caring about what it's supposed to represent. It's the same problem that I have with people taking Flaws instead of "taking away points from things that will actually give me a disadvantage". People decide to play regular heroes, but call themselves "Infernals" and do everything they can to downplay actually being at all infernal, just so they can get Charms.
I guarantee you I'd have nothing against Infernals if I ran into Infernals who were actually interesting. But I don't.