Having lived in New Orleans, I am VERY picky about my shrimp and how its cooked. Of course, now that I live in the desert I learn to make do since fresh shrimp is very hard to come by. Its my experience that most people (including restaurants) have a tendency to overcook shrimp. Raw shrimp is translucent; when cooked, it turns a nice pink color. Overcook it and it will become mealy.
To cook a bag of shrimp, add 3 cups of water and a wedge of lemon to a saucepan. Bring to a boil over high heat. Reduce heat to medium, add thawed shrimp and cook for 3 minutes. Drain but don’t rinse.
If you really want to get fancy and mimic southern-style shrimp, add a teaspoon of Cajun seasoning or Old Bay Seasoning mix to the water while its boiling. Then you really don’t want to rinse it or you’ll wash away all the yummy goodness.