I hear you!
I totally disagree with spanking, and if I find out that a friend of mine spanks her kid, I just won't get engaged in a conversation about it, because we're going to wind up angry with each other. Most of my friends are very respectful of their children, so this rarely happens, but I have had a friend or two admit to the occasional spanking. What I noticed was that, upon telling me this, the friend in question always felt the need to offer a defense (i.e., "Well, I've tried everything else, and nothing works, and I just can't have him doing X."), so it was clear that she did not feel comfortable spanking. Not only that, but it is also clear that they are then expecting me to somehow assure them that yes, spanking is justified in this instance. And I just won't do that. I won't. So I say, "You know what, this is a bad subject for us to discuss because I just don't believe in any form of physical punishment. Let's just agree to disagree and change the subject."
If a person wants my advice on alternative techniques, I'll give 'em, but not if they don't ask.
Fortunately, though, almost none of my friends spank.