No, I haven't.... Makes me wonder about the liquid you are using!!!! Are you vaping some of the real acidic liquids, (ie.. cinnamon type).... 2+ years with an eGo and no green stuff in my threading.... In fact, this is the first i've ever heard of it..... I would tend to lean to the plating that is coming off, but certainly not the brass under the plating.... Looked around on the forum and nothing!!!!
when i vaped with an ego, it was mostly sweet juices.
with regular cleaning, no you wont see it.
but after having that ego in a drawer for a while, it will be there, if ANY type of moisture was left in that connector.
The threads were well used, so the plating had worn off by that time.
worth noting that these were real Joyetech eGo's, and not clones.