Can't answer because this hasn't happened to me. I've only been in the hobby around 5 years at this point (give or take a year). While it's technically a cheap hobby - you just need pencil/paper and a free SRD or equivalent - it's expensive if you actually want the prewritten adventures and settings books. So I am very careful in what I buy. Now, I do have a couple digital books I bought from dndbeyond - Staircase and Radiant Citadel - that I haven't run yet because we've had higher priority things to run, but so far I haven't bought anything I hated. I am also planning to buy Daggerheart mostly for the art (which goes against being careful, but I am considering it a coffee table book rather than a TTRPG book). I'd like to run it, but I'm already having trouble finding enough time to run the systems I already own - Tales of the Valiant/D&D, Cosmere, Pathfinder 2e, and Starfinder 2e.