Agreed with Chuck, the number of QC problems some people are reporting sound nutty. I am not doubting, just commenting that I've not seen that many. I have, however, seen a number, and I share the overall opinion that something is not right with the large number of bad bins coming off the line. For binoculars among myself and friends, across 14 pairs that I've seen / used / handled in the past few years that I can think of, the following issues:
Diopter drift x2 (Monarch HG, Zeiss Conquest HD)
Broken strap attachment lug (Zen-Ray)
Loose optic inside barrel (Swaro)
I do think there are more quality isses than there ought to be. Personally I'm a bit perplexed by the frequency of focuser and diopter problems at the higher end. In lower end binoculars of course this is where there will be a lot of issues (I guess along with hinge tension). Without knowing a ton about binocular focusing mechanisms, but knowing about mechanical engineering in general, I would view this not as a QC problem but as an engineering problem. If 5, 10, or 25% of the new cars rolling off the line had steering problems or developed steering problems within a year or two, would you suggest a QC issue or an engineering issue? This is clearly all engineered to a certain price and weight and a lot might be gained by not trying to shave the last 20g and $20.