They never reported a "NotABug." They could back up every report, and give exact reproduction steps.

They found weird, obscure corner cases, and that was by hand (they hated automation tools).

They had 3,000-line Excel spreadsheets. If even one of those rows failed, the whole shooting match (like an entire product line) could come to a halt (so that meant they had to cross their t's, and dot their i's).

They seldom had "opinion-based" reports, and, when they did, the report was presented by the manager, after long discussions.

The company I worked for, was renowned as one of the highest-Quality optical corporations in the world.