When I am sure my plane is assembled correct, I have used this procedure to determine if my elevator throws are correct and to make adjustments. It will also tell you if you are compensating for a twisted aileron or not.
ORIGINAL: Bax
One way to check is to do an inside loop from upright flight and then an outside loop from inverted flight. See which wing tends to roll to the outside. If it's the same wing panel (say, the model's right wing panel), then you have a weight problem. If its one wing panel in the inside loop, and the other wing panel in the outside loop, then you have a misalignment somewhere (wing warp, ailerons not aligned, bent fuse, rudder off, elevators not aligned, and so on).