I never heard of the green hand shake until last year, and it wasn't from here; it was from a current Elder. I was having a conversation with him about how does a CO support themselves in old age. He told me it was very common for the CO and his wife to receive $20 from members in the congregation. In fact I believe from the conversation it is actually encouraged. He told me he knew a few CO that save enough in 30 years to retire comfortably in Peru and other South American countries.
I was a naive child when active, and was only aware of the free food and lodging. I didn't know about the green handshakes. Even in poor congregations that could be $100 to $200 in a week. It might not sound like much, but tax free and no expenses that adds up fast.