bottom of the barrel, scraping the barrel, or scraping the bottom of the barrel

자료: http://www.answers.com/bottom%20of%20the%20barrel

Idioms:

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]

자료: Collins Cobuild

7. PHRASE : V inflects
If you say that someone is scraping the barrel, or scraping the bottom of thebarrel, you disapprove of the fact that they are using or doing something of extremely poor quality.[ INFORMAL ]