We regularly planed the face off cards - like forests - and glued on a colour copy of a pricey card in its place.
But since we were good people, and even though the fakes would fool a kid or a noob, and even shuffle and cut the same, we intentionally sprinkled the copier with yellow confetti so each fake would have some obvious yellow dots.
And we'd ensure everyone knew: "these 6 cards are proxies for these other 6 cards, and in an ante game you win the real card with the proxy. Fair?" It was usually cool.
Our white-hat counterfeiting game was on point. And card sleeves were lame. ;-)