For me, it’s a very low percentage.
There was this $2 AA “police” torch I got from eBay, once; trying to cut corners and wanting something with LD20 aesthetics, I submitted myself to ordering it. The middle tube was the only bit worth keeping, as a 2xAA extension for the SK68.
Of the bunch of Tank007E09 I had just ordered, one has to be tightened unusually hard to get it to flicker (not to work, actually) - and so far, the communication with FastTech’s consumer service has been a breeze. Going to send it back later this week.
Then, there was this pretty AA anglehead with the magnet in the tailcap, which stopped working after being dropped only one time.
So, in conclusion, I am quite happy with a very low number of defective lights. On the other hand, dry threads and untightened switches do not count for me, as I dismantle everything I get, anyway, to clean, inspect and relube properly.
I’ve said it before, the Chinese are quite capable of high precision work and quality control - whenever they take these matters seriously. Western contractors just interested in quantity and the lowest price possible haven’t helped matters in the past decades.
When an item said “Made in China” in the 1970’s and 1980’s, one could have rest assured it would be as long lasting as it was cheap. Things have changed a lot; today, a product made in Shenzhen and sold from Hongkong doesn’t necessarily raise the yellow flag of caution anymore.
You remember the third “Back to the Future” film starring Michael J. Fox and Christopher Lloyd?
Dr. Emmett Brown: “No wonder this circuit failed; it says ‘Made in Japan’.” - Marty McFly: “What do you mean, Doc? All the best stuff is made in Japan!”