I have some direct experience. Recently, one of the blacksmiths had to put out a small fire and found out that most of his 5 extinguishers did not work. This was alarming to me, and I did a web search. It seems that there are a bunch of fake extinguishers floating around. I used to work for a safety conscious company and there were a lot of extinguishers around. I ended up with a bunch of old ones around the house, about 7 of them, some of them more than 10 years old. So, I decided to have a party with the neighborhood kids. I got out a bunch of large sheet metal trays and a gallon of camp fuel. The kids all went to town testing the extinguishers. (I heard later on that one of them showed calm and confidence with an extinguisher in a subsequent real incident.) None of the extinguishers had been shaken in years. No dead blow hammers. Every one functioned perfectly and put out the expected sized fire. I intended to repeat the experiment with some cheap Costco new extinguishers, but my lawn died and I am going to have to find an empty lot. A web search said that the contents of the dry chemical is non-toxic to plants. You can't believe everything you see on the web.