The kind of situation I'd expect to see more often in real life is that NPS scores are inflated for fun luxury goods, because they naturally inspire more enthusiasm, and deflated for essentials, because very few people are even capable of getting excited about socks.
Mostly I was meaning to hint at, where I've seen things like NPS go off the rails is when people assume they measure what the marketing pitch says they measure. The reality is invariably more subtle.
