After reading another thread where baby names are being declared Chav or schemie by the op and a few others my blood is boiling a bit.
I live in Scotland and the phrase schemie gets used interchangeably with ned and chav.
I think schemie is by far the worst of the three. Chav and ned are nasty terms of abuse, but refer to a type of behaviour/manner of dress /lifestyle that the (ignorant) speaker is describing.
Schemie goes a step further (a housing scheme is the term used in Scotland for council estate) implies that an undesirable person or behaviour in type of behaviour is exclusive to and representive of people who live in local authority housing. My mother, grandparents and a lot of my friends grew up in council homes and not a single one of them display behaviour which could be described as 'schemie'