As I think (assume? hope??) that the XP-value of the node has something to do with the quality of it, I tend not to ++ nodes which have some technical errors in them (such as suggesting code which doesn't do what it says it does, which means the poster did not try it). Such nodes might even warrant a --, esp. if they are an answer to a question from a newbee.
CountZero
"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law