I was once served lukewarm potato salad tasting of vinegar. I actually walked it back to the restaurant kitchen and complained. They apologized and brought me HOT potato salad. Ha! I'd never had German potato salad and thought they had served me something rancid. Everyone in the south knows, you don't eat lukewarm potato salad that has started to go off. : )
Live and learn. But, I still can't abide the stuff.