Taste/Feeling:
* As bitter as gall: This is a classic and powerful simile, emphasizing intense bitterness.
* As bitter as unripe fruit: This emphasizes a sharp, unpleasant taste.
* As bitter as the taste of defeat: This emphasizes the emotional bitterness of failure.
* As bitter as a betrayal: This emphasizes the sharp sting of being betrayed.
* As bitter as the wind in winter: This emphasizes a piercing, sharp bitterness.
Appearance/Metaphorical:
* As bitter as the shade of a poisoned apple: This uses imagery to convey a sense of danger and unpleasantness.
* As bitter as the memory of a lost love: This highlights the emotional pain and regret associated with loss.
* As bitter as the truth of the world: This emphasizes the harsh realities that people must face.
* As bitter as the disappointment of a broken promise: This emphasizes the feeling of betrayal and letdown.
The best simile for you will depend on the specific context and the type of bitterness you want to convey.