How to determine minimum and maximum angle for cheap servos?
I think you have 2 choices: either measure and store for each one individually, or find the worst case for all of them and code around that.

Do you really need the full travel? If you're using the servo to push/pull, the servo-travel endpoints are pretty weak anyway.


  I wanted a robot look left and look right, which is 0° or 180°.


Maybe you can make up the limited angular travel of the servo in the linkage between the it and the camera platform.