Prediction markets might also help, a la truthcoin, by rewarding those who make the best guess.

nostr:npub1nevsewvjqhrsmpfcpdqw6v3e9f6z8w9sq0yt8kpndk2cumw8g6hs5mjmve

Wikifreedia or wikipedia, or any central repository both suffer from similar limitations for the user in determining truth.