I don't know which is worse: the bar person who warns you that the mild you've just ordered is dark, or the bar person who pulls the mild and then says "ooh that's dark isn't it?"
Person number one is perhaps trying to be helpful, but I don't need warning thanks. I usually associate mild with darkness and I'm not frightened by a bit of colour.
Person number two should know his product. Pulling a beer for a customer shouldn't be the time they discover what that beer actually looks like.
Maybe I'm a moody old git but both these scenarios wind me up.