When you buy a package of pre-washed salad, should you wash it anyway? Not
really. Health experts say if lettuce is contaminated with the kinds of
organisms that can make you sick, washing it won’t protect you. What’s more,
the typical kitchen sink is so germy, you’re more likely to splash
bacteria onto your ready-to-eat greens by cleaning them at home.
Source: Good Housekeeping, 10/12