Yes, and these cheap devices sadly don't have accuracy description. I would be OK to pay for it if some accuracy would be guaranteed, but writing that it's calibrated and not specifying the maximal error looks always fishy.
I would also be wary of how the accuracy declines over time. E.g. how does the device keep properly sized dust from staying or small scratches from developing on the surfaces that are involved in the measurement (e.g. lenses and mirrors for optical devices)?
Especially when there are very similar [1] devices selling in China for about 1/3 the price (where bad air quality is more than what you cooked for breakfast).