Please help settle a debate/argument.
You and several other folks go out for dinner at a local, family-run place. You order cocktails, a bottle of wine, apps., mains, and a couple of desserts. Food is mediocre (in fact, you don't bother having any of the left-overs boxed to take home - and you ALWAYS take home left-overs). Service is pretty bad (in terms of botched orders, kitchen not producing all of the mains at the same time, server disappearing for long periods of time, water glasses never refilled) but it's not the worse you've had. Still, by the end of the meal you know that you'll not be returning.
And then you get the bill. What's this? It's suspiciously ... lower than expected. You start to scrutinize it and discover that your server has either decided to (unannounced) comp. you the cocktails AND bottle of wine or (more likely, especially given that the wine was listed at about the same price as the four mains combined) forgotten to include them on the tab.
Some at the table argue in favor of letting the server know about their oversight and asking for an adjusted bill. Others argue in favor of paying, leaving a decent 25% - 30% tip as a "thank you for the oops," and hightailing it out the door.
What do you do?