I think on this it would more mean, if you had to fill a cup with your saliva only, then drink it, there would be aversion to do so. However if it stays inside your mouth the whole time as regular saliva then the aversion wouldn't be there.
The question comes down to, why the sudden aversion to drinking it?
I think it's mostly psychological, but if I had a cup of my own spit, it wouldn't last very long, it would quickly start to break down. And that would be unpleasant.
So I think as much spit as I could fit into a cup in 15 minutes sure I could drink that no problem. Any longer than that and then you start having to worry about the breakdown and that's going to change the flavor.
Oh I agree, it is absolutely psychological. I was only providing context for you because most people would absolutely refuse to drink it. I myself have a pretty negative history with saliva and would refuse to drink any amount once it's left my mouth; regardless of the science behind it.
I'm pretty sure most people already know it's a psychological aversion but the why is the question. There is seemingly no reason for it