I turned my disagree button off ages ago, as soon as I found out how. If I disagree with somebody I'll tell them why, and that way I don't accidentally hit "disagree" when I'm surfing on the iPod. The bigger benefit is that I can't see others' disagrees on my posts, which suits me fine.
I got flamed in one forum for mentioning that a fast food place messed up and made DH's burger with everything. There's a whole lot of screaming and hair-trigger assumptions, but that's just the world now.