I need a post I can drag out and throw at people when they get confused so here it is.
PLEX is not an ISK Faucet. Nor is mining, wormholes (with one exception), or station trading (with one exception). Destroying a ship is not an ISK sink, its actually an ISK faucet.
An ISK faucet as a mechanic that generates ISK out of nothing and puts it into circulation. Similarly, and ISK sink is a mechanic that takes ISK from circulation and destroys it.
PLEX is a mechanic that moves ISK from one player to another but neither creates or destroys the ISK (except a miniscule amount in the order taxation).
Mining ore and minerals and then selling them on the market does not create ISK as it comes from another player.
Destroying a ship produces an insurance payout making it an ISK faucet and not a sink since ISK is created and not destroyed.
Wormholes generate wealth but not ISK, excepting the blue data cores in Sleeper wrecks that players take back to empire space and sell to NPC buy orders. In fact, all NPC buy orders act as an ISK faucet because they create ISK out of nothing to give to the player sellers.
NPC pirate bounties are a big ISK faucet, as are the Sansha incursion payouts. Loyalty point stores, on the other hand, are ISK sinks since players give ISK along with the LPs and tags to get items.
ISK in a character's wallet can be sunk if that character gets perma-banned. Players that unsubscribe and don't come back sink their ISK too, but a returning player frees their ISK up again.
Aurum is neither an ISK faucet or sink as it does not generate or destroy any ISK in circulation.