Back in the 1980's I was asked to run a night class at the local high school for amateur winemaking. I was very surprised to find that in the class of about 25, 20 of them had already played at it and 5 of them had their own still! (Which was illegal back in those days). They had made wine out of everything from 2nd hand tea leaves to grass clippings!
For the second week, I suggested that all who had made something bring it along and we'll have a 'critique' evening. The school had given us a laboratory room for the classes, so we had lots of sinks and water taps so we could sample, spit and rinse out. The quality of the samples brought ranged from absolutely wonderful to bloody awful, but the main problem seemed to be too high alcohol levels. They just kept putting sugar in until it stopped, which meant we ended up at about 18-21%. The evening devolved into a heavy drinking session under the guise of analytical sampling to the point where when it was time to go home, several missed the double door entrance to the room and hit the sides.
As for yeasts bakers yeast will work but there are different strains of yeast that give slightly different characteristics. For that reason very few winemakers rely on natural yeasts as it is difficult to guarantee the ferment will be clean.
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Civilisation is a veneer, easily soluble in alcohol!