The condition one finds oneself in on an extremely hot day, or doing particularly heavy work. To Sweat profusely in an unattractive manner. Especially true if sweat makes your trainers/shoes soggy. Happens a lot to overweight people.
From the Liverpool argot 'Scouse' - a runny nose, a pun on diarrhoea. Probably a skit at the glassblower's trade which would involve some straining, a hazardous practice for someone suffering any looseness of the bowels. (There is a traditional glass industry at St. Helen's, on the Mersey estuary east and inland of Liverpool.)