When a client refused to pay for proper subfloor work
Years ago, my mentor would have turned down the job. I needed the work, so I debated doing it their way. Have you ever taken a job knowing the prep wasn't right?
Ugh, been there. I once laid tile over a cracked slab because the homeowner wouldn't spring for the full fix. I did talk them into a liquid waterproofing membrane at least (it was a band-aid, but better than nothing). Held up for a few years before they had to call someone else.