That explains a lot! So, brining works only if the bird is farm fresh.
When selecting a turkey that is going to be brined, be sure it is not pre~basted or that it is not a kosher turkey. Brining turkey that has been pre-basted is not recommended. Pre-basted and kosher turkeys have been processed with a salt solution to maintain juiciness and if brined, they may end up being too salty. Also, if the turkey is over-brined the result will be meat that is very soggy.
From: http://www.recipetips.com/kitchen-tips/t--433/Brining-a-Turkey.asp