Sluagh don't go in for secret societies and hidden conspiracies, per se. From a certain point of view, the entire kith is one giant secret society, and as for conspiracies, they have more than they have spiders. Instead, they have only one social ritual that they all, even the most rebellious Unseelie wilder, take part in. High Tea.
The procedure is simple. A sluagh decides to they want to host a High Tea. They send invitations to up to a dozen other sluagh, who respond. On the appointed day, the guests arrive, each bearing a story and something to add to the feast. Bearing in mind that in fae mien the sluagh subsist on weak tea, sour wine, stale cake, and the like, it's probably best that members of other kith aren't usually invited to attend.
Once the gathering officially starts, the refreshments are served in cracked cups and chipped plates. It's not that the underfolk are cheap; indeed the glasses and settings for High Tea were usually quite expensive at one time. Rather, High Tea is making a statement about decay, and what the sluagh themselves once were. For that reason, the crystal goblets have spiderweb cracks and the hand-fired pottery plates have cracked edges and flaking glaze. Prematurely aging one's dishes is déclassé.
Tale-telling, or more accurately, swapping information, is the primary activity at High Tea. The secondary purpose is to reaffirm the local crawler pecking order; it's a way to check up on who's talking too much, who doesn't know how to set a proper table, and so on. Finally, it allows them to perform a sort of census of themselves. Antisocial at the best of times, the underfolk often go for months without seeing another of their kith. A High Tea invitation, even if it is refused, is a way to inquire about a kith-mate's well being without intruding.