There are two ways the scallops are handled and sold: soaked (wet) or dry.
Soaked scallops are shucked directly into a bath of phosphates. This process helps preserve the scallops for a longer time, but it also results in them absorbing water and plump up. This will result in the scallops having a tougher texture and being less flavorful.
Dry scallops are shucked into a dry container, with no water or preservatives. Their flavor is more pure and concentrated. They have a shorter shelf-life, but they will also be fresher.