Looking for just that.... cam lean.
This is something that I do very quicky when I'm working on a bow that has a split buss cable.
I take a good straight (often aluminum and full length) arrow and press it to the side of the idler or top cam. What I want to see is the arrow running parralell to the string on both sides. If the idler or cam is leaning one way or the other, some twists in the appropriate side of the buss cable are needed. Its a quick and easy way to minimize limb torque. It is probably one of the most often overlooked tuning tools, and is a direct cause of unexplained poor broadhead flight (shooter error not withstanding).