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
This is a very, very common thing amongst Irish people when describing a person, place or thing. Because sometimes we can't articulate how large or small an object is, or the skin tone of an individual or even the heat of a local curry dish - we use this a lot! We basically just say the word twice and the person who gets the info knows exactly what we mean by tone alone.