that is a good question. i think you still have some good stuff in there because your never going to remove only heads or tails in feints there will be some good stuff mixed with them...as much as a pot stiller woud have...no no even close but enuff to save and give a good squeeze later. imho
GOT BAIT?
small children left unatended will be sold as bait
I throw the fores and heads from a reflux run into the container for holding sterilising/cleaning/firestarting/weed and ant killing spirits. It is my home made methylated spirit.
Tails I ditch. By the time you have extracted the ethanol, they ain't much left in those stinky stinky tails. Much easier and more productive to do a new ferment then re-run reflux tails.
Just checked the heads and tails jars from the last run. Heads 93.5% tails 55% (and ran into tails far longer than I normally do).
I would suspect the heads contain considerable ethanol as the other things coming out with them cause flavours and smells detectable by humans in ppt or even ppm. I toss 70-80ml fores from a 20l wash so I rerun heads and usually tails.
The sterilising ability of foreshots I find useful when cleaning glass stuff like bottles for wine. It saves having to use chemicals and thus saves a few pennies.