Maybe we've been lucky, but Mrs. clarence5ybr and I have never been on the receiving end of a dirty look for no additional tip when it's included. Not only that, but the one time Mrs. clarence5ybr added an extra couple of bucks for a person who had been especially helpful (and was delivering lunch for the third day in a row while I was at a conference), she was even told 'you know, the tip is included, you don't have to add anything'. She responded that she knew that was the case, but wanted to add a little extra.

Our room service at the Hyatt Regency in Denver last night did clearly label the line "additional gratuity" after listing the 'service charge'. I think this is the minimum that should be done to help remind the customer that gratuity is already in the bill. I'll add that this isn't the sole problem of room service...if you dine with a large party at a restaurant, you will often trigger the mandatory gratuity clause, but the bill will still have a blank line for tip.