Your most disappointing purchase or audition?

I've had a few.

bought a Naim Nait 3. Loved it in the store. Returned it within a week- way forward at home

Brought home some CJ preamp to audition perhaps 22 years ago. Noisy as anything and a turn off transient destroyed a tweeter (though years later i bought a CJ 17LS2 which I thought was the finest preamp I ever heard in my home)

Auditioned a VPI table (HW19) in a store- the store just could not get the belt to stay on. Bought a Rega instead. This was in perhaps 1990.

Fortunately, I never really experienced buyers remorse say 6 months or more after settling on a piece of gear.

Finally, there have been too many speakers that got stellar write ups which I just didn't care for.
08-08-14: Drubin
It's disturbing to watch a public meltdown.
Yes amen Drubin, get rid of the trolls & lets get back to friendly discussion on this hobby!
Went up to the SF Bay Area to audition speakers. Heard a Krell B&W system. At least it was a nice drive there and back, because it was a total system failure.
"Lloyd, did you audition or purchase her?"

Purchased. Still paying. No resale value.

The audition was under deceptive "show" conditions. As is often recommended here, an in-home audition, with your existing system, is required to identify and avoid incompatibilities. Or a meltdown.