That's true in many countries but decidedly not so in the US, where service people often live on tips. US citizens abroad are not trying to offend, they are using home-grown instincts. A British visitor to the States who leaves 50 cents on a $50 bar tab is giving just the same amount of offense, unwittingly or not. Tipping culture is very complex.

As for the room service question -- if you add a 20 percent tip to an automatic 18 percent gratuity, that's a nearly 40 percent surcharge -- too much. That said, when the automatic gratuity appears, I tend to round the bill up about $2.00 anyway when I sign the chit. If the delivery guy gets the auto-gratuity, great; if he doesn't, it only took him five minutes to bring the tray upstairs, so $2.00 is about right.

I don't think anyone expects RS to be a bargain -- that's the price you pay for eating on the bed in your sweats. For some reason my son loves room service, thinks it a highlight of our trips together, so I go through this a lot.