I was actually thinking of this too and talked my trainer. Here is the message she sent me:

"I don’t like them much at all, although sometimes if it’s a family being evicted due to barking problems, or taking the dog to the shelter, I’ll sometimes recommend giving one a shot if it is in dire circumstances and it will keep the dog and family in its home. They don’t cause pain, in the way that a shock collar does, but they DO cause a dog to be uncomfortable by spraying a burst of citronella oil into the dog’s face, nose, and sometimes eyes. Many people think they are less aversive than shock collars, because they don’t use electricity, but what a lot of folks don’t consider is how important a dog’s nose is to their world, and how dogs understand scent. Knowing about how much better a dog’s sense of smell is than ours, and how important it is, it may even be more aversive (it doesn’t have to be painful to be aversive!) than a momentary shock because of how long the oil sticks to the nasal passages, hair, etc.

The secondary problem that they come with is the same with the shock collars – once you start using it, if it is effective, you’ll probably be reliant upon it for life, because dogs become very knowledgable about when the collar is on versus off. Most dogs who need to use these collars cannot be weaned off of them, and once you do, the behaviours come back quite quickly. This is because the dog has learned by context, and the behaviour depends on the presence of the collar.

That being said, of course dogs who are trained using food rewards will always need random rewards for good behaviour throughout its life (as any behaviour will only persist as long as it is either reinforced once in a while, or punished for lack of compliance). The learning component is no different. But personally, I would much rather use rewards for good behaviour, over the life of the dog, than punishments for unwanted behaviour, for the life of the dog. "


Not sure if this is useful, but it made me rethink this collar.