I have read that there is a way to get the numbers to bleed through temporarily on lotto tickets. Have you ever scratched off an instant ticket that was very different from most? For example, the coating was sticky or hard to remove. Sure it could just be old tickets, but what if it is something else? I do not know if it is possible to use mixtures of chemicals, especially solvents to get the numbers and symbols to bleed through. As an end consumer, it is of no use to me, because even if that worked, I would still have to purchase the tickets to find out. That takes away the whole point.
Assuming that this is a possibility, then what would keep a closing clerk, or especially the owner from doing this, sight unseen, after hours? What if they were to unroll the pack, and add the chemicals. They could see which ones were the winners and write down the information or memorize it. If the tickets were to dry back to a normal consistency, without any sign of tampering, they could do that, with their customers being none the wiser. After they sold all of the losers and "small" winners, they then buy or steal the ticket which they know to be the winner. The question is whether or not this is possible, and if so, what would keep them from doing this, especially on older tickets that they were having a hard time selling.