If we are talking nightmares do what I did on Tuesday , cleaned a suite and did my usual amazing job

As I was cleaning the living room I didn't put any dust sheets down, (why should I , if I make a mess off the carpet it doesn't matter)
The overspray had lightly wetted the carpet, the suite had mohagany feet, I'm sure you can guess the result

not just dye marks but huge stripes where we had pulled the suite across the carpet.
Luckily they cleaned out but I was crapping bricks as we cleaned the carpet,
A rookie mistake, not to be repeated.