Some things are likely picked up automatically, e.g. listings with knife in the title. Other breaches of rules likely rely on either admin spotting them (they can't vet every listing) or users reporting them - which means that some are bound to slip through. That that happens does not negate the rule though. Bringing the errant listings to admin's attention is unlikely to further your case - just get the errant listings removed (which may give you satisfaction - but probably not much ).