The term "bad hat" is often used to describe someone who is dishonest or undesirable. Synonyms for this phrase include "rogue," "scoundrel," "ne'er-do-well," "culprit," "miscreant," "rascal," "villain," and "blackguard." These words all have a negative connotation and suggest that the person being described is up to no good or has a dubious reputation. "Bad egg," "troublemaker," and "delinquent" are also commonly used synonyms for "bad hat." Whether you're looking to insult someone or simply describe someone who is untrustworthy, these synonyms are sure to come in handy.