leave a sour / bad taste in one's mouth

/lˈiːv ɐ sˈaʊə bˈad tˈeɪst ɪn wˈɒnz mˈaʊθ/

/lˈiːv ɐ sˈaɪʊɹ bˈæd tˈeɪst ɪn wˈʌnz mˈaʊθ/

to leave a sour / bad taste in one's mouth

to leave a lasting negative effect on someone

Examples

1. Of course Andrew not inviting me to his party leaves a sour taste in my mouth.

2. I think we all felt he'd been treated very unfairly and it left a bad taste in our mouths.

3. I've been in positions where I've mentored people and and sometimes when they don't show up it definitely leaves a bad taste in my mouth.

4. Yes, and it left a bad taste in my mouth.