For MY ears, Heil ESS AMT-1. Had a pair in my house for two weeks and the shrill top end was unbearable.
Anthem Integrated 225 - that great sounding POS always broke down.
Any NAD amp. I've had 2 and hated them both. Also had a Dynaco 400 that was ok except for the fan. It sounded like a B-29 when it turned on. I had 2 AVR receivers I didn't like. An Integra and an Onkyo which both sounded decent for HT but awful for music.
In 1985 I got my first CD player - I don't remember the model number, but it was a Sanyo. I bought it because of a review that said it had " the heart of a thoroughbred". That may have been true, but I never found out because it had the legs of a newborn colt. The thing skipped all over the place, with any CD. I returned it to the big box store - they didn't have any more in stock, so gave me a refund. I then went to a real audio store and bought a Yamaha CD300, which I'm still using after replacing the belt recently. This is not the current Yamaha CD-S300, but the CD300 as pictured in this auction. Disclaimer: I have no affiliation with the auction and am not advocating you do anything beyond look at the picture. Besides, the price is almost as much as I paid in 1985.
The funny thing is that I used to sell audio equipment. We sold Sony, Yamaha, and a couple of other units as well. For some reason, the boss decided to take on some Sanyo, and we laughed at him. That BOTL Sanyo played every single disc we could find, including the discs that the Yamahas and Sonys couldn't begin to play. We were amazed.
I think I've only ever bought one piece of electronics that was essentially useless junk: a Realistic 31-2020 graphic equalizer.
It was great looking with a silver aluminum faceplate in the early days of BPC, didn't add any obvious distortion to the signal path, had a generally quality feel to it, and had a neat spectrum analyzer display that appealed to my teenage sense of drama.
However it was overly sensitive to something in the power supply in my parents' house because it would wink out at random intervals, about once every couple hours, causing a complete drop out of all sound before coming back on a split second later. It was under warranty, but the Rat Shack techs couldn't find anything wrong with it, so it ended up in the bottom of a closet, then the trash. Pretty much turned me off to the Realistic brand forever.
Back in the 80s, I bought a Technics turntable (model ??)to replace my old trusty BIC 960. The Technics was a mid-priced ($150 or so), P-mount AT cart, plastic base, direct drive I think. It sounded decent but had a severe static electricity problem: it would emit a loud static POP! at random points on all records. No amount of prep or antistatic devices would eliminate the problem. The same multiple POPs! would always appear on every records.
I finally sold it.
Very easy answer for me.....a Pioneer SX-980 that I bought new in the late '70s. So unreliable. Spent more time being repaired than being used. It was beautiful to look at, and loved hearing those big switches lock into place, but it was junk.
As for the Shure M97xe, I've had three of them, and yes, IGD seems to be a problem, but replace that stylus with an SAS, and the results can be amazing. Also, a stock M95EJ stylus sounds fantastic with this cart (have both, tried it myself).
I don't know if it was the worst thing ever but it was my 1st foray into stereo. I had a Zenith drop down suitcase stereo. The speakers like wings would open up and were on pin hinges so you could remove them for that stereo seperation sound w/ about 15' of wire. I tried but I have not seen another example ever. This when and now I'm going into the way back machine where spindle stacking started and about 5 records dropped on one another.