Analysing - extract three

Tunes for Bears to Dance to by Robert Cormier

In this extract Mr Hairston, who runs a shop, is talking to his young assistant Henry and making comments about his customers.

quote
"The customer's always right," he proclaimed one day, as if he could read Henry's mind. "But only in the store. When buying. Otherwise, they're only people. Stupid, most of them. Don't even know a bargain when they see one. So, why give them a bargain?"
Question

(a) What is unusual about the way Mr Hairston speaks?

(b) What does this suggest about his character?

(a) Mr Hairston doesn’t use complete sentences/the sentences are short.

So 'When buying' would normally be 'When they are buying things' 'Stupid, most of them' would normally be and 'Most of them are stupid.'

(b) This makes Mr Hairston sound arrogant/short-tempered/abrupt.