Sorry lot offered at auction, endless baggy trousers (1,3,3)
I believe the answer is:
a bad egg
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for a bad egg that I've seen before include "One undesirable customer" , "one's worthless" , "Someone inherently dishonest" , "A worthless person (colloq.)" , "Unpleasant guy" .)