did you just raise the car and test it? or did you leave a load on the lower control arm when you tested it.
see, since your springs push down on the control arm, there is always pressure on the ball joint. The way we check them at work is to put the jack under the control arm (basically eliminating the pressure from the spring) and putting a long pry bar under the tire, and lifting upwards. I bet you will notice a bunch of play in them if you do it that way. I thought the same thing when I did mine (several years ago) But once I pulled them out, and held them upside down, and realized how loose they really were...I knew that I finally found my noise!