What's a boring spec that turned out to matter way more than expected?

Been thinking about this after going down a research rabbit hole on luxury cigar humidors of all things. Weird category to end up in, but it turned out to be a pretty good case study in a pattern I think shows up everywhere in product design.

At the entry level of that category, almost every product looks and performs about the same. But once you get into the higher tier, the marketing copy across brands starts converging on the same vague language (premium materials, precision engineering, timeless craftsmanship) while the actual functional differences get harder to spot unless you know exactly what to look for. In that specific case it turned out to be things like active vs. passive climate control, which is barely mentioned on most product pages even though it's the single biggest factor in whether the thing actually works a year from now instead of just on day one.

That got me wondering how common this pattern is elsewhere. The "looks finished" layer and the "actually holds up" layer feeling almost decoupled, where you need fairly specific domain knowledge to tell which brands are solving the real engineering problem versus which ones are just polishing the surface.

A few examples I can think of off the top of my head: mattresses (foam density and edge support vs. how plush it feels in a showroom), noise cancelling headphones (ANC chip quality vs. how good the marketing demo sounds), and apparently high end Afidano cigar storage too, where the interior lining material and cooling mechanism matter way more than the finish of the cabinet.

Curious what this looks like in categories other people here have actually built or researched deeply. What's the spec that barely shows up in marketing but is actually the thing separating "good on day one" from "good after a year of real use" in your space?