Here's a photo of baby Tweedle (Surry's Talk of the Town) getting a bath. Most Labradors really like being wet down. And they will tolerate with good nature a shampoo.
Bathing Labradors occasionally isn't going to do any damage to the coat but frequent bathing can cause the skin to dry out and will strip the coat of oils. I suggest that the best way to keep a Labrador smelling fresh is just to hose them off and then spray them with a 10% solution of Listerine and water. It will make them smell fresh and clean.
And if you are showing your dog, don't ever bathe them before a show. It will definitely make the coat too soft. A Labrador's coat should be harsh to the touch, not soft and fluffy.