> their reviews are complete black boxes They are certainly not "complete black boxes". This page [0], for example, explains in detail their test procedure for

> their reviews are complete black boxes They are certainly not "complete black boxes". This page [0], for example, explains in detail their test procedure for vacuum cleaners. Just an excerpt on durability testing (via deepl): > Impact test (500 cycles): The hoovers drive over thresholds 10 000 times and bump into posts 1 000 times. > Drop test: The suction nozzle must survive 1 200 drops from a height of 80 centimetres. > Cable pull-out test: 6 000 pulls. > Test of hose attachments: 40 000 swings with the connection nozzle clamped. > Squeezing the pipes, hoses and auxiliary air adjusters: The testers load them with about 70 kilograms for ten seconds. [0]: https://www.test.de/Staubsauger-im-Test-1838262-1838266/ https://www.test.de/Staubsauger-im-Test-1838262-1838266/