One thing that MUST be checked, whether you're buying or just maintaining, is the main suspension bolt at the bottom of the rear shock. It doesn't often fail but when it does it's catastrophic. The bike collapses onto the back wheel, which locks and you need some pretty superior emergency braking skills to stop in a straight line. When it happened to me I was in the Cedarberg, just came out of a pass and was fortunately on the straight!
I replaced my bolt with one of higher tensile strength.
I replaced my bolt with one of higher tensile strength.