sour

Lemons have a sour taste.

Don't drink that milk; it's turned sour.

His sour breath makes it unpleasing to talk to him.

He gave me a sour look.

sour land

sour gas smells like rotten eggs

Let me embrace thee, sour adversity

Unlike what the name implies, there is nothing inherently wrong with a sour note: It is perfectly well-tuned note that would sound normal in another context (and which presumably would not sound sour to someone unfamiliar with tonal music).