Grain of salt American British phrase
If you say you take something with a "grain of salt", it means you do not believe completely in something that people told you.
Although I love Josh for his generosity, I always take his word with a grain of salt.
Even excellent doctors make mistakes, that why you should take everything with a grain of salt.
To express that you don't believe in something that someone has just said
1. That's a bit more expensive than expected.
2. That's rather unfair or untrue.
To suspect that someone is being dishonest
Said when you do not trust what someone has promised