What has always disturbed me a little about WebmasterWorld are the colors of the design. It just always looked so "anonymous" to me.
I know it's utterly stupid that it makes me feel this way, but a design such as the one over at searchenginewatch (just a random example) seems to give a forum a more "professional look" to my eyes. I can only mention again that I know its utterly stupid it makes me feel this way :D, but perception is reality isnt it?;-)
(That being said I like the content on this forum much better than at most others Im aware of, at the moment)