Agreed, or the wheel has been damaged to the point that it can not be serviced properly (i.e. bent rim). Then again, that goes back to a competent wheel guy telling you so. I recently replaced a spoke for a heavy rider who was getting his wheels trued or spokes replaced at the shop every 2 weeks. Upon inspection, I realized that they had used different brand and thickness of spokes, different length nipples, and different length spokes. There was one hop in the wheel that was almost 1/4" deviation and it left the spokes with no tension in that area, even if the nipples were out of threads. I informed him that the wheel was not serviceable anymore and recommend a new wheel or at least a new rim and spokes.