Rachel Cooke for The Guardian:

A man (or woman) who is actively unpleasant to waiters is best avoided. Ditto those who patronise them. I've written all this by way of a plea: please be good to your waiter. I know it's annoying when things aren't right. I know it's galling to be given a hefty bill when all night you've been wondering why the table that came in after you was served before you. But waiters are mere messengers most of the time, and it's wrong to shoot them, however bad the news.