I believe in a healthy fear. When I was young my parents used to spank me. I was such a horrible child, I made babysitters run away crying ;). For that, I would get a spank because it's hard to find someone that would babysit me. It worked on me though, because eventually I knew that if I did something wrong, dad would come home and let me know I did wrong! I have nothing but love and respect for my dad, because I know he loves me, respects me and didn't WANT to hurt me. I was one of those kids that just WOULDN'T listen.
Eventually I grew up though, and the spankings had to stop. At one point, I remember my dad approaching me to spank me and I threatened to run away and never come back. I think they realized that that was the time for them to stop spanking me, or I would forever resent them. Because they never spanked me again. It was time for more grown up punishments.
Granted I was kind of a screwed up child in high school. But that had nothing to do with my parents spanking me. It was more-so my social awkwardness and being made fun of all through elementary school by the other kids.
I have read a lot of your replies and I do agree with you to point. Some kids don't deserve the spankings they are given, but I guess if that's how a person wants to raise their child, that's how they'll do it. As for ME, when I decide to have a child. I will do everything in my power not to resort to spankings. They worked on me, but I'd rather not risk losing the love and respect of my child :)