Combination of persistency of the nip-05 (how long without change), your WOT follows indicator (more likely to be the real deal if many of your follows also follow for a long time) + some activity metrics (replies, likes, boosts ratios etc. for not spam —> depth/quality of content)?

Similar to if somebody has been on Xitter or IG for over a decade with regular posting and following —> gives higher trust that it’s the real account.