Multiple times I remember reading or getting advice that [ingredient X] needs to be washed in cold water before preparing and that warm water will... not precisely ruin them, but somehow make it worse.
Now, I don't remember precisely which ingredients those were... fish maybe? Or mushrooms? Could be some other vegetables too.
Anyways, this advice always has seemed suspicious to me. The difference in temperature between cold and warm water is maybe 30°C, not really enough to do anything chemically I think, and warm water is so much more pleasant for the hands... And especially for ingredients that you intend to cook right afterwards anyway, what harm can it do?
So - are there any ingredients that actually need to be washed in cold water, otherwise it negatively affects the quality of the end result? Preferably ones that are not super exotic.