What's the worst high-end set-up you've had?

While stationed in Korea, I had Polk 5+ Jr's placed atop 7ft tall room furniture with one speaker facing southeast and the other looking northwest five inches from the ceiling.
The speaker cables were Monster Livewire automotive, IC's were Monster 400's@$25 a pair(purchased every payday).Akai cassette player, Yamaha C-80 w/parametric EQ and Carver 1.0 amp.
I said I would never need another system again....then I got stationed in Japan.
Worst, huh?

Krell entry level KAV 250, BW 9NT, SONY 444ES as preamp, and all Monster wires. It was so revelaing you could tell what color socks of the musicians were wearing... some were not up to participating in maiking a fashion statement of their own.

Only time it sounded good was on rainy nights around 2AM.

Did I mention my ignorance of ground loop issues at the time? Well, even afterwards, it wasn't good.

It pays to address a system's requirements as you go... cables... isolation... synergy... power lines... etc.
I have had several because I did not address my cables and power.
A complete Gryphon system, cables and all, on loan from a dealer. Didn't work with my Quads and Sound Labs I had at the time. Dead, lifeless, edgy, but very hifi.....)-:
Krell integrated, Coincident Tech Conquest, Musical Fidelity E624 CDP. So bright and edgy it torn the enamel from my teeth. Skull piercing, ear icepicks where no amount of adjustment or cable changes would tame the sonic pithing this combo delivered.

This configuration lasted one week before I traded the Conquests for Dynaudio 50's and sold the Krell. The E624 is still in secondary use nicely matched with an Electrocompaniet AW70 amp and a Promethius passive preamp.
Celestion SL6S being driven by a Carver Receiver and connected with Monster Cable IC's and speaker cables. Grating was the best it could do. A Counterpoint SA 3.1 and Sumo 9 fixed that problem.
Entrope, that's funny, man!

That's by far the best chuckle I've had all day.

Unhappily it is also an accurate description of the sound.