You avoid them by describing the condition honestly using standard grades, photographing both sides, and showing any flaws up close
Giving that knowledge to opponents is often good since it can delay them doing what they otherwise might have, offering us a time window into other action
Now, you may have up to 15 cards in a sideboard, and can add or remove cards as you see fit, so long as your decklist remains legal
Unfortunately, Bane's not exactly friendly towards your other face-down morph creatures
Still quite a few to collect, going for all english and japanese including all variants like shadowless base and the reverse holos
Or you might end up like the Pokmon dad who held on to every card because his kid loved themwhich, come to think of it, is a pretty great outcome regardless of the market price