From Longman Dictionary of Contemporary Englishhave seen better dayshave seen better daysinformalCONDITION/STATE OF something to be in a bad condition Her hat had seen better days. → see
Examples from the Corpus
have seen better days• Ms. Davis's car had certainly seen better days.• Virginia's car had definitely seen better days.• We are working at Nanking University, in rather cramped and primitive conditions, for the buildings have seen better days. 