plants are supposed to be wet and then dry again, but if they can't get dry again because they're in a fridge sometimes this can be bad. so estelle's claim makes sense but it depends on the vegetable and where you get it. if it's dry enough again before storing it doesn't matter that much. there's exceptions like carrots that are supposed to stay dry, if you wash them the skin opens up and they quickly start to go soft and brown. rucola/rocket/arugula/whatever for instance i always rinse and then store in a wet towel in a plastic bag and it stays fresh for longer than if i don't do all of that. but those are outliers maybe. i usually get mine from the farmer's market, supermarket stuff is treated differently again before it's on the shelf. as a rule of thumb though, just leave it as it is and wash it right before cutting it seems like the right move.

Yeah what ixlander said was mostly along the lines of what I was thinking. Primarily if its wet and not properly dried before storage then it opens it up to the possibility of rotting