Will admixture spoil mayo?
I learned as a kid that mixing anything into (commercial) mayonnaise will cause it to spoil much faster. Therefore, I was told, don't even put a wet spoon in: the small amount of water on the spoon will adulterate the mayonnaise.
Is there anything to this? A quick Google search finds me nothing. If so, is it specific to mayonnaise, or what else does it apply to also?