I billed a customer more in parts and labor to fabricate magnetic catches to hold speaker grilles to his ceiling then it would have cost him to just buy the speakers in the first place.

He was also mad that the millwork guys cut his wood ceiling around the pre construction brackets.

His bid was for us to prewire the house and install 8 pairs of in ceiling speakers. After the house went to finish he wanted to "revisit" the idea of having house audio, that it was too much money.

Same guy had us wire his house for video distribution and is/was now mad at us that there was no place for his cable box in the family room.

Another customer (an engineer) had me program a remote to control his family room system. I program said remote, issue a power off command, gear turns off. Wait a minute and go to turn it back on and the tv makes a loud popping noise and goes dark. He looks at me and says (somewhat angrily), "why did you turn the tv off? It blows a fuse in it when you turn it back on, I never shut it off."
He insisted that I drive across town to Radio Shack (this was a while ago) and find/install a replacement fuse for said ancient CRT rear pro tv.

I have another client that has a very large, very old Crestron system in their house. Place is completely automated. Lighting, shades, hvac, pool, gate etc.
They found us when their processor died. We quoted a replacement and programming, they were aghast at the price and decided to "think about it".
Fast forward 6 months, they finally call us back to do the job.
These are people worth north of $100,000,000 and they had extension cords run all over their 8 million dollar house and lamps everywhere because they had no lighting due to the processor being dead. They would go in the closet, roll the rack out and manually adjust the thermostats and walk all the way up their long, steep driveway with a gate remote to let people in.
We quoted an update to their system, they have been "thinking about it" for about a year now.