Green’s Dictionary of Slang

bottom-shelf adj.

inferior, cheap.

2013		E. Kurz ‘Pegleg’ in ThugLit Aug. [ebook] I was coming out of the liquor store with my bottom-shelf bottle.
2013		T. Pluck ‘Six Feet Under God’ in Life During Wartime (2018) 187: I took a slug of bottom-shelf rotgut for breakfast.