Anyone can self-pin (under 30 troops or pure spies are 30% under period.) they can also have mates hit em after they bank for that last bit of gold
20% btw, and if a pure spy has 0 gold, he cannot be hit as well. Though a pure spy with 0 gold but not spy-pinned, can be stolen from for gold.
On an empty land click and then -> build and scroll down to guild building. Pure spies are players with only guilds