Of course sadism is vital... it would make very little sense if the enjoyment of our activities were one sided wouldn't it?
however I doubt that many dom's are true sadists, i.e just relishing the thought of making others suffer. Since we know that we are giving "pleasure" at the same time, its difficult to really separate the pure evil in our dark hearts from the pleasurable experience of our subs.
Admittedly, I look upon inflicted pain with a great deal of pride... watching a nice little mark building on freshly beaten flesh does excite me much more than what mother would approve of, so I guess yes... am definitely a sadist in that sense.... however I cannot stand by and watch innocents being treated badly, with that I mean unwilling subjects and outright meanness. In the lifestyle we chose its a fine line between pleasure and pain... for both the inflictor and his/her victim. It would be a darn shame if we did not all get our jollies from it.

If you did not like this post, I have just proven I am a sadist by making you read it... (insert evil laugh here)