My husband was on the Gulf Coast during the peak of that oil spill last summer off and on for 3 months. His whole crew ate fresh shrimp and fish every night they were there. No one got sick.
If it smells bad, tastes bad, why would you put it in your mouth ? You wouldn't but BP was handing out checks so what the hell. Why not get some of that. Not defending BP, what happened should never have happened but when people see dollars, they get sick REAL quick. Know what I mean ?
You should never handle raw seafood without gloves. NEVER. If the shrimp were contaminated, most likely you got sick from getting stuck. Not from eating it.
Never buy shrimp off the dock from someone you don't know. There are people that sell whatever. That's what will make you sick and they don't care. Always ask. The reputable people will tell you where to go.