Of 98 dogs:
9 totally blew off the spray from the beginning.
7 had success for 1 week or more, then the correction stopped working altogether, meaning that
the spray became a completely ineffective correction for any undesired behavior.
3 responded to the citronella in some situations, but not all, from day one.
5 had success for 100% of undesired behaviors for at least 2 weeks, then the owner stopped using
the collar altogether.
1 of the 5 retained verbal warning response.
4 of the responses declined very soon after stopping use.
6 were so affected by the spray that it could be classified as an over-correction (eliciting
profound anxiety and fear responses)
3 of the 6 had to stop using citronella as a correction because the dog could not recover
from the correction in a reasonable amount of time.
10 had 100% success for a week or more, then the correction was effective for some situations, but
not all.
64 had 100% success - the correction was effective in each situation it was applied to.

Keep in mind, the collar can be misused by people. It was impossible for me to make this a controlled case study, simply because I couldn't watch my clients every time they used the collar. I'm sure some of them overused the collar, causing the dog to become desensitized to the spray. I'm also confident that some of my clients underused it, or sprayed at the wrong time- too soon or too late. I still think the collar is worth a try. If the correction is effective for your dog, you have the benefit of being able to stop a behavior from far away, and, if you do it right, the dog won't know it's you who is doing it. You become way more powerful and worthy of obedience if you can get to that point.