> My logic is that

I just assumed a bit of water in advance would prevent toothpaste from directly/easily adhering to the bristles, keeping more of it "in useful circulation" as it were.

> kinda gross

A few months back I needed some hydrogen peroxide, but the available bottle was more than I was likely to use before it degraded into H20... So, naturally, I started messing around looking for other applications. (It worked great on certain oily gunks that resist isopropyl.)

One weird outcome from that is I've been putting a drop on the bristles of my toothbrush, although it's more of an idle experiment to see if the foaming action dislodges visible crud (i.e. toothpaste near the base) in-between uses, as opposed to a disinfection right before use.