When I was first learning the little tricks to having success with AMA C/L combat, I noticed that the top dogs could sight down their planes' trailing edge, from the rear looking forward, and spot right away if they had an out of trim plane. If you try to fly one of these models too far out of trim, a 2 horse NELSON can destroy the 9 oz airframe within a couple of laps. I think it is interesting that an ARF foam wing could pass a QC check and get slammed into a box being so far out of whack. Over in one of those factories, a rejected part would probably cost someone a job.