Can you see my hand in the air? They get clogged up, they spray in the wrong directions and just plain don't work. I've thrown many away (across the room too).
It is just so very simple, flux is sticky. It dries out in the spray parts and then won't work. At the end of the work day, turn them upside down into a glass of water or your quench bowl
It works. It's amazing. It's so simple and effective. And think how much money you will save between therapy and having to buy new spray bottles.