"Senior brother, quick, tell me, what mischief are you up to this time?" No sooner had they left that place, Su Youyi couldn't wait and stared at Liang Yi with sparkling eyes, she didn't believe her senior brother would let that person off so easily.
Black market transactions fully depend on the discernment of both parties, a willing buyer and a willing seller. If one finds out the goods are fake after purchasing, they can only blame their own lack of discernment and cannot go back to dispute it; otherwise, it would break the black market's rules.
But if one discovers this issue before the transaction and counters it, then it wouldn't violate this rule. After all, you can't only allow sellers to deceive without allowing buyers to counter, right?