Ya won't catch any flies with vinegar
Heard in Donegal
Used to describe a person that is very polite or Charming for their own gain. Example Business people can be charming or "Sweet" to customers. If customers see them as igornant or "Sour" they will not shop there Hence the phrase Ya wont catch Flies with Vinegar.
John: "Da new manager in the shop is wile friendly speaks to everyone" Francie: "Ah sure ya won't catch any flies wi' vinegar now wil ya"
The newly appointed shop manager is exceptionally cordial and converses with every patron.