The replies on the "1953 Canada's Textile industry stamp" thread swung into the area of hidden designer initials, etc. Perhaps it would be worthy of a new topic?
I like to look for the designer's name on this stamp (Switzerland #136a), because if the full name(C. L'Eplattenier)is there rather than just the initials CL, then the stamp is worth about $40 instead of about 40c.
In the example below the L of diagonal CL is mostly obscured by the cancel. The full name would start much lower and to the left and would terminate where the L is.

