BMW: Rear suspension ball joints loose on 740iL 2001, bmw suspension, ball joints

Question
I had the tires of my 740iL balanced because I'm getting a strange shaking sensation at between 40 and 65 MPH (even the steering wheel shakes back-and-forth).   The service center that balanced the tires said they noticed the real tires were very loose when they put them back on, in other words after tightening them back on they were able to move them up/down back/forth like the ball joints (upper) were worn and needed replacing as soon as possible in their words.  Is this an accurate assessment or does the BMW suspension and all of it's sophistication require it to be "loose" like that when up on a lift?  (The tire balancing helped but there's still a hint of shaking at the speeds above... they said that they had to check again that they tightened the rear tires since they "were so loose").   Any help is welcome!

Answer
Tom,
To be honest, I've never messed with the suspension on a 7-series.  But it would make no sense for a 7-series to have completely different suspension than a 3, or 5-series.  These cars have quite a bit of bushings that all can wear out.  The rear is less likely to show these symptoms though, because it has one less axis of rotation (they dont turn like front wheels).
 I dont know how many miles are on that vehicle, but for it to be "wore-out" is kind of a stretch.  I own a '99 3-series, with 100k miles, and it is still really tight.  But if you have 200k miles, or the car was driven on dirt roads.... it's possible.