The trail past Green Lake and up Glines Canyon is currently clearly marked. After following the sign for West Lake at the first junction, the trail passes a campsite after 200 yards, does a quick switchback up the hill, and shortly comes to a second sign noting Green Lake to the left and West Lake to the right. Head left.
Also I do not believe the trail is just a use trail- perhaps a no longer maintained one? Though overgrown in a few spots there are places where limbs have been cut so they are no longer blocking the trail, and the switchbacks through the talus to Virginia Pass appear constructed.
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe