I agree they certainly should not be used on all dogs, and I would never recommend anyone use it in the way I did. I think you have to know the dog you are dealing with and the reaction you are likely to get. However my bitch was the boldest noisiest animal imaginable even at 8 weeks. No one could be heard, and the only way we could interrupt her yodelling and get her attention was to shake the bottle. We used it briefly to get her attention it actually worked really well, she would look straight at you and in the silence you could then issue a command. Dispensed with entirely within about 2 weeks, but within that timescale the volume was decreased until it was barely a tinkle and then just picking up the bottle was enough. (And she does still yodel when happy and playing, it has to be heard to be believed)