Ok, both the OFF Clip-on and the Thermacell only work if you are sitting in one spot and not moving. Also, they cannot be used around food that is uncovered. So for hiking or cooking/eating, they are not useful at all. They also can't be used indoors or even in your tent, so another big negative.
I used the Off Clip-On while in my screen room and got no bites, altho, I WAS in my screen room so there probably weren't many, if any, mosquitoes in there anyways. I brought it with me to the beach but the wind was so strong, that the bugs weren't an issue there anyways.
The Thermacell I used while at the campfire. It takes about 10 minutes to do it's thing, so maybe that was when I got bit. Altho, I didn't actually see or hear any mosquitoes around me. (Did make S'Mores, but I haven't died yet, so apparently they didn't get contaminated
)
The rest of the time I was moving around, setting up my tent, etc, or out hiking, so I probably got bit up some then too.
There are plastic "bracelets" that can be worn on wrists and/or ankles to keep mosquitoes and ticks away. Will try those next time. I mostly got bit on my legs.
Not sure if any of my research was helpful or conclusive...