I've never really understood the Greggs hatred on Mumsnet
Well, I suppose because it's cheap, high fat, high carb comfort food, and it's indicative of a certain kind of poverty - another stereotype of class/money/poverty/lifestyle.
And maybe some people (or kinds/classes of people) wouldn't like to be associated with buying that sort of food, because of what it would seem to say about them. For coffee puffs, I don't really care.
If you want the sociologist's take on this, Pierre Bourdieu has a concept called "habitus." From Wikipedia:
"Habitus is one's physical and psychological demeanor as a result of habits developed over a period of time.[citation needed] It develops a person's attitudes towards society and influences the way that an individual reacts to the world around them. Habitus is a structuring feature of life and is determined by a series of influences on the individual, such as one’s socio-economic status, family, religion, education and ethnicity.[citation needed] That is, the attitudes, mannerisms, ideologies, actions and habits that a person has been subjected to in their personal life manifests to create the person that they are today. Therefore, an individual is a result of the internalised influences throughout their life."
habitus