A significant portion of the blandness of some supermarket foods is the result of processing, with "pro-juiciness" treatments being some of the worst offenders. Chicken (even whole chickens for roasting) are injected with water, oil, and water-binding compounds to plump them up. The water mostly evaporates during cooking so the result is usually blander rather than juicier. Most hams sold today are cured by injecting…
Chicken is injected with water combos not simply to plump them up, it's called a brine. By all means buy your poultry without being brined, I prefer mine with it. Here's a nice "why" people do this: http://www.realsimple.com/food-recipes/cooking-tips-techniqu...
And either way I'd rather pay not $5/lbs or whatever for water.