His video on Water Purifiers only measures one dimension of water purification: TDS measurement. This leaves out a whole world of other aspects to consider when testing water and filtration quality. While TDS can give an indication of cleanliness of the water you can only glean from what you can measure, to this end the TDS measurement will not catch all contaminants in the water because it relies on electrical conductivity.
Also he does not disclose that his TDS measuring device is actually bundled with one of the devices he is testing. Should have used a third party tool to verify that it is giving an accurate reading instead of a unit bundled with one of the water filters as a marketing ploy. It gives some doubt as to how seriously he takes his other tests. These are the things you miss if you don't actually know any better(I assume the majority of his audience have not looked into what makes good water filtration before watching his video).
Nevertheless, the fact that he is really the only one doing these kinds of tests is enough to give him some sort of super reviewer credibility.
From his pod casts it looks like Linus (Linus Tech Tips) is building his lab up to be a massive consumer review machine, can't wait for that to happen. But I doubt they'd be able to tackle the massive amount of gadgets like USB cables, USB hubs, USB docks, chargers, air purity weather stations, etc. Plus their reviews often aren't in-depth enough for people to make their own mind up on stuff.
Linus has mentioned that part of the intent of LTT Labs/Lab 32 is to not just release video reviews, but to produce comprehensive datasheets on products with some sort of open-access release model. I think the video they did testing HDMI cables[0] is sort of a prototype for that.
Also he does not disclose that his TDS measuring device is actually bundled with one of the devices he is testing. Should have used a third party tool to verify that it is giving an accurate reading instead of a unit bundled with one of the water filters as a marketing ploy. It gives some doubt as to how seriously he takes his other tests. These are the things you miss if you don't actually know any better(I assume the majority of his audience have not looked into what makes good water filtration before watching his video).
Nevertheless, the fact that he is really the only one doing these kinds of tests is enough to give him some sort of super reviewer credibility.