The true meaning of the word sadist, is indeed getting a kick out of giving pain, but with complete disregard of the 'victim'.
People calling themselves sadists because they like to inflict pain to a masochist need further scrutinizing (the act, not the folks) as there's a strong possibility that their sadism is instigated by the masochism of their partner.
Torquemada, Mengele, François Alphonse Donatien De Sade, they are true sadists and thus dispicable as, indeed, there was something wrong with them.
Also, it is not because people define themselves as being something that they are.
I have been a passenger on an airplane. As a result, I could define myself as an aviator. But the fact that I would do so doesn't make me one...
Dunno if you noticed, but there's more than one person who contributed here
JJ