My guess is the "priming" fluid in CE2's isn't priming fluid but it's probably PG or VG (could possibly be a China tobacco but I've noticed no smell to it) ...
If it is, it is the Lowest Quality junk out there.
There is a Very simple test that we did when "Mystery Fluid" first appeared in CE2's.
And that is to take a New CE2 and do a quick Dry Burn to make sure that there is Nothing on the Wick/Coil. Then put a drop of Pure PG or Pure VG on the wick and hit it.
I think you will find that it tastes Nothing like what "Mystery Fluid" tastes like.