Bad
frazzled - To feel completely exhausted and worn out, and unable to think straight, after a great deal of mental or physical effort
After being up two nights in a row writing a 60 page history paper, and drinking 60 cups of coffee, Simon's mind felt frazzled.
preposterous - Contrary to reason or common sense; utterly absurd or ridiculous.
When Sandy's stock broker called and suggested that he sell half his stocks because he felt the market was overvalued, Sandy thought the idea was preposterous - but it turned out that his stock broker was right.
caustic - Sarcastic or severely critical, often in a hurtful or biting manner; or able to burn or corrode organic tissue, typically referring to chemicals or substances.

The caustic chemical spilled onto the floor and quickly started to eat away at the floor surface.