Nobody wants to eat bad clams, especially if you're eating them raw. Knowing how to tell if your clams are good or bad not only ensures that you'll enjoy the taste, but may also save you a trip to the doctor.
Smell your clams before you buy them. If they smell like anything other than the sea, they may already be bad and you should not purchase them. Be sure to let the seller know the clams are not good so an unsuspecting shopper does not take them home.
Inspect each clam and set aside any that are open or have cracked shells.
Tap on the open-shelled clams and throw away any that do not close immediately. Soft-shelled clams do not close completely. If the clam shell moves when touched, it's still alive and safe to eat.
Discard all clams with cracked shells.
Test the remaining clams by pulling on each side of the shell. If the clam opens or falls apart, it's not good and should be thrown away.
You should cook your clams the day you buy them, but they can be kept in the refrigerator for up to two days. Keep them in a bowl covered with a wet towel. Do not soak them in fresh water. It not only kills the clam, but also affects flavor, according to Fine Cooking.
It's not safe to eat partially cooked or raw clams if you have liver disease, cancer, diabetes or an immune-compromising condition such as HIV/AIDS. Young children, pregnant women and the elderly should also avoid eating any undercooked or raw seafood.