While
挖苦 is a form of sarcasm, not all English sarcasm translates to
挖苦. English sarcasm can be situational irony or dry wit that isn't personal (e.g., looking at a terrible storm and saying, “What lovely weather.”).
挖苦 is almost always personal, targeted, and carries that essential “bitter” (`苦`) feeling. The Chinese word for broader, more literary sarcasm or irony is `
讽刺 (fěngcì)`.