When the never smoked/vaped hubby has a nightmare that I started smoking again but I have never had that nightmare. 
When charging your batteries dims the lights in half your neighborhood.
When you buy a new toothbrush just so you can use your old one to clean threads on your mod.
The windows in your vehicle always have a film on the inside from your vapor.
I would have continued using it for at least another month if I hadn't replaced it so I don't see how it's any more gross to use it on my mod with toothpaste than it is to use it in my mouth with toothpaste....EEEeewww... I bought a cheap one for that use. I don't have a problem using an old toothbrush for around the sink and tile grout, but somehow using an old toothbrush for my tanks and mod just doesn't seem right.