If you don’t trust the manufacturers, you’ll have to find an expert to trust, or tear down the bulbs and examine them yourself. The best way to know for sure is to measure the current being driven through the LEDs and compare it to their maximum rated current. The ones that don’t last long are usually being run at their maximum current, producing a lot of excess heat which shortens their lives dramatically.

I don't think it's untrustworthy in a sense you are deliberately lied to. I think more likely problem is that there is quality control issues and entire batch of particular bulb is compromised, like can happen with anything else - hard drives, RAM, pencils.

In general it's quite reasonable. Cheaper bulbs failed on me, more expensive ones work just fine for many years.

One thing is I wonder about if phosphorus (or whatever chemical they use) is burning out over the years. I.d. do I get worse light quality as these bulbs age?