Glass in displays comes from TFT factories in large sheets called mother glass and is sorted by classes. These classes are governed by ISO standards which identify three levels of allowable number of bad pixels.
Apart from the visual discomfort bad pixels cause, there are very important practical disadvantages to working on a screen missing a seemingly tiny dot. The importance will vary across industries but it is perhaps best illustrated in medical devices where even a single bad pixel may change image enough to lead to wrong conclusions and dramatic consequences.
In our 10.1” displays we add an additional layer of tests as standard so we do not miss a single item with a bad pixel. There is a 100% ZERO bad pixels guarantee.