I did notice today that my WTG pullets earlobes have a very distinctive GREEN tint to them instead of being white or blueish white. Maybe you can distinguish between the EEs, the WT Blues and the WT Greens that way?
I have one True Green. She looks like a slightly lighter than normal Welsummer...but there were a whole range of red or reddish coloration's among the TG pullets on the farm I bought her from. I think it would be almost impossible to tell a True green from an EE or a True Blue with all the color...