I stopped buying cartridge-based games a long time ago (3rd to 5th gen. mainly), but back when I did, I only looked for games that were clean and with their labels intact. As Warmsignal said, no point in wasting money and effort if it’s not going to stay in my collection. However, many years ago I did end up getting Super Turrican 2 for the SNES absurdly cheap in a small lot; it was missing the front label and the shell was filthy. While the cart was given a good cleaning, it was still in rough shape, so I ended up swapping the board to a much nicer one, although it’s still missing the label. I wish the same thing happened again, but the game being Aero Fighters instead. That’d be aces.
Coincidentally, my copy of Ocarina of Time has both its labels faded and worn, but it was actually a hand-me-down. Been meaning to replace it a multitude of times, but I just don’t care enough to do so.