In the midst of a lot of business travel, I have seen a lot of poor restaurant practice at play. Two that irk me the most:
1) Delivering the entrée very shortly after the appetizer was delivered.
--At dinner recently, my entrée arrived 5 minutes after my appetizer. The server did not acknowledge this at all and merely piled the additional plates on my table and left. I called her over and explained that I had literally just gotten my appetizer at which point she took my entrée and stuck it under a heat lamp, saying nothing to me during the course of this "interaction." I asked if they could re-make my entrée once I was finished my appetizer and was told that my entrée would be "fine" as it cooked and got desiccated under the heat lamp. I left after the appetizer
2) Serving a glass of wine from an "old" bottle (e.g., one opened 2+ days ago)
--At another restaurant last Tuesday (that was closed on both Sunday and Monday), I ordered a glass of Cab. We're not talking a great Cab with massive longevity either . . . probably a bottle that goes for $25 retail (yes, a mediocre list if I'm being nice). I asked the waiter if it was safe to assume the bottle was newly opened that night. He assured me they "dated" the bottles. Once he looked at the bottle, he told me that it was opened the previous Friday and then quite confidently told me that "This will easily hold up for 7-8 days." I politely asked if he would mind opening a new bottle.