Applestar, you started this thrread in 2013? and STILL haven't made any wine? Shame on you!
Anyway to address your comments: I haven't heard of toxic substances left in the original part of a drinkable wine from which spirit has been (illegally

) distilled. Maybe the reference you saw was to dodgy recipes for home made 'bathtub' spirits. (Shades of Bob Dylan; "
Get you a copper kettle" ...)
It's not all that uncommon (haha) for folks who've drunk too much, to say there must have been something toxic in the booze. There was - alcohol!
Anyway my wife & I have been making wine for decades (without very sophisticated equipment) both from kits and from harvested produce - also make vodka-based liqueurs - with very few absolute failures (some of those resulted in flavorful vinegars which got bottled for Xmas gifts.) We've made 'country' wine from many things including dandelions, peapods, rose hips, just about anything we could grow or scavenge. Country wines, lacking high-sugar grapes, nearly always need a lot of sugar in the recipe; 2.5 to 3lb per pound of 'fruit.' Our favorites nowadays are a faux saké made with rice, raisins & sugar; and a rhubarb and ginger wine which also uses sugar. Ah there's also 'Grandma's Sherry' at Xmas, made with oranges, raisins, potatoes, and of course sugar.
We enjoy making liqueurs - the main one using blackberries and sugar in Vodka. We strain off the finished liquid and freeze the alcoholic berries as 'Adult Blackberries' for use in trifles and other desserts. We've always used vodka as the spirit base. I can imagine that brandy and the like might over-complicate the flavor.
By the way you mentioned distilling liqueurs. I wonder if that would even be possible; the alcohol content may alrready be as high as you could get it (or would want?)
C'mon, get started in making wine !!