Can excessive negative camber be due to worn shocks?
 

I think the negative camber on my rear wheels is excessive. The previous owner of the car said the only real mechanical problem he had with the car was how fast it went through rear shocks.

How can I test for worn shocks (I have the $$$ adaptive ones) and could this explain the camber?

If the camber is excessive when the car is stationary, it's not the shocks. They have no function then. If the springs are too short or the mounting pads have collapsed, that will increase negative camber. Have you checked the ride height? At least you can change the rear camber with shims.
If the ride height is correct, and the camber in spec., the shocks could be a problem if you lead- foot that SC engine.

I would recommend replacing the factory Axle Shims (probably 4mm) to the thickest available, 7.5mm.

I did this when I installed Lowering Springs on my car.

Thanks for the advice, guys. Where does one procure 7.5mm shims and is installation a DIY job?

moderatly yes, but its a pia, and youll need to realign when done as changing camber changes toe. Also acceleration squats the rear suspension and will increase negative camber as a result on accel. But, if youre -1.5* or less you should not have a camber wear issue

Agree, I have -1.2 and -1.5 camber on the rear and there is no uneven wear after 10k miles, I have a slight toe in to help correct and all is good. In fact, same in the front too with the toe in.