Grapes that I took out of the fridge yesterday and left in the car overnight in a gladware thing. What do you think? They were so expensive...argh! lol
Grapes don't have to be refrigerated, they won't spoil from not being in the cold, they'll just rot faster. If they aren't all shriveled and mushy they should be fine.
Smell them. If they smell fine and don't have mold on them, they are fine. They definitely don't need to be refrigerated. And you'll know if they are bad if they are soft, mushy or have a sour taste.
I leave grapes in a bowl on the counter because I don't like them cold (I have sensitive teeth). Plus with them out, I see them and eat them faster than if they are in the fridge where I forget about them.