bottom of the barrel

The least desirable, the dregs, as in The nominating committee had trouble finding candidates; they were settling for the bottom of the barrel. The phrase often occurs in scrape the bottom of the barrel, meaning “to use the least desirable elements” (because one has no choice), as in Bringing up that minor legal point proves that you're scraping the bottom of the barrel. This metaphor for the sediment left by wine in a barrel was already used by Cicero to describe the lowest elements of Roman society. [First half of 1900s]