A 'saltbreather' is a person who lives by the sea and has spent too long living there, having breathed in 'salty air' all their lives they tend to go slightly mad, have a warped sense of right and wrong plus very poor fashion choices. Often criminals and with a higher than average serial killer count per thousand.
I went to the seaside last week and the saltbreathers working in the arcade started hassling me, I mean them odd balls have lived by the sea that long they don't even know how to talk to someone properly without insulting them.