I purchased a pair of cheap eyeglasses at walmart, only to find them, at time of pickup, with two right-side lenses. To make an analogy, it was as if they'd given me a pair of shoes for my right foot. The mistake was so blatantly visible, that no minor oversight can explain - whoever put these glasses together paid no attention to what he or she was doing whatsoever. But I don't blame the individual, because as it is he/she was probably grossly underpaid.
In addition, the frame corroded easily, and broke down the center after exactly 11 months. Because I needed a new pair in a hurry, and because I partly blamed the failure on me, I purchased a second identical pair, only to see it too corrode and break down the center after 7 months, exactly as the first did. The frame corroded easily and broke after 0.5 - 1 year, despite claims that these were made of titanium alloy, a downright lie, because titanium alloy would never corrode and failin so short a period of time of average usage.
I could complain about walmart service but I won't. I restrict my complaint to the horrendous quality of the glasses I purchase: and hey, they've gotta cut cost somewhere. In all honesty, I'd rather they cut in quality than cut it via third world sweatshops that employ child labour, but neither is justifiable.