Glad you asked...
You can tell by the color. If it's not gray, they are not good. You can also tell by the smell. Never cook bad seafood, you will definitely get sick.
rpatin     How-To Expert
Then again, this answer might help you...
If you purchase shrimp and it is slimy that is a good indication that it is bad. A fishy odor is also a sign that shrimp is bad. Shrimp should not have a smell to it.
rachelk     How-To Expert
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