Extinguishers always have some type of pressure gauge or test button on them, along with a gross weight to indicate a proper full charge. As long as you look them over every once in a while, the odds are quite high that they will
work. But most folks don't realize a "liter" sized extinguisher is about enough to put out a trash basket or a skillet, and a grease fire will often just spread if you hit it with a regular extinguisher. Either way once it spreads, you need more extinguisher, FAST. And they're all not the same, not all equally effective on everything. Then there are the
cushions, which are almost always urethane foam, which produces nasty toxins very quickly and also makes darn good fire kindling.
Will they
work? Almost always. Will that be good enough? Maybe.