The first, on the corner with Muirkirk Road, shows that the barber's/shipping agents used to be a butcher's shop. More precisely, it was 'R. C. Evans, Family Butcher, Purveyor of English & Scotch meat, finest quality, lowest prices'. Evans appears to have occupied the premises long enough for the sign to have been repainted at least once: traces of the earlier lettering show through.
Nearby Inchmery Road has two signs. The first, sadly, is near-illegible although tantalising traces of the words remain.
However, the second was rather more exciting. From Sandhurst Road, a large sign for Warner Bros, Hygienic Bakers is visible. Walking down Inchmery Road, though, the side of the building revealed that this building also advertises Hovis. The use of the Hovis logo in conjunction with details of a local baker was characteristic of their campaign, but it's the first one I've seen making use of two walls of a building in this way.