Here's a short list of memorable equipment I had experiences with ranging from....erm....interesting to downright awful. Most of these I encountered in the early and mid 1990s:
Tascam TSR-8, 1/2" 8 track with dbx I NR. Decent sound quality, and reliable in my experience, but you always had to turn the dbx on manually every time you turned the deck on. Also, the NR was only switchable in groups of 4 tracks, not on an individual track-by-track basis. (With one multitrack tape I had to mix one time, this was indeed a problem!) It also took forever for the tape to come to a stop when in either fast wind mode, and most aggravating was when you were in record, and you hit stop to punch out somewhere, it continued to record for about 2/3 of a second--still rolling tape--after you hit stop! (No doubt it needed some serious modding of its logic control circuitry!)
JBL 4208 monitors. How can I describe these? Buddha boxes? Beer belly blasters? Pregnant cyclopses? 8 inch woofer in a moulded grey enclosure with a somewhat bulgy, if not quite bulbous shape, with said woofer in the centre of the bulge, apparently to make it 'time-aligned' with the titanium-diaphragm tweeter on top. This tweeter was zingy and aggressive and tended to lead me to mix things that sounded dull elsewhere. The next speakers in the studio where these were, were worse.
Tannoy System 10 DMT monitors. The replacements for the JBLs. Looked snazzy, but made everything sound awful! A monitor speaker should tell you when something's wrong with the sound, but you should be able to have things sound right when they ARE right, too. This, they could not do. They had a metallic peak at 2100 Hz that could razor your ears, and the highs had no real clarity. Loud, but very poor definition. I ended up having to take mixes home, listen to them through an old Altec-Lansing A7-500, determine what was 'off' on what I heard, make notes as to what to change, and by how many dB or whatever, drive back to the studio, and make those fine adjustments, and do the final mixes that way, to achieve anything of quality with them.
Alesis D-4 electronic drum module. My introduction to the dreaded digital 'latency' syndrome. This was painfully evident when I used it to try and replace a poor-sounding bass drum track on a rock band's recording, using the BD track to 'trigger' the D-4. My fix, to put the D-4's sound in correct time? Dub the original BD track through a digital delay, and record the delay's output to an open track, with the multitrack tape on the machine upside down. This track (ahead of things by 18 milliseconds) was then used to trigger the D-4. Worked the trick, but still....I gave notice, that if I was ever to be forced to use a D-4 or other of its ilk again, I would quit recording. (I didn't have to quit.)
ADA MP-1 'MIDI programmable' guitar preamp/processor. These were around back when guitar players just had to have 'rack' gear, using something like this feeding a rack-mount solid-state amp, driving a run-of-mill 4X12 cabinet of some type or other. Classic items such as made by Fender, Ampeg, Marshall et al were electronica non grata. Some of the most horrid guitar sounds I ever recorded around 15 years ago, were generated by these MP-1 units. Dark, grungy, murky, muffled, dull, soupy, and just garbled. Lots of push buttons, and lots of LED lights, that didn't seem to change the sound much, if at all. (I wonder if I should have recorded a direct feed out of one of these, instead of the traditional miking of a speaker in the cabinet?) Stranger still, these have one or two 12AX7 tubes in them, that barely even get warm at all, never mind hot. You could unplug them from the unit while it was on and hear no difference in the sound IIRC!
Marshall mosfet amps. I recall seeing these come into a friend's music shop very frequently for a period in the early and mid-1990s. No sooner would a tech get them rebuilt, that they would blow up again. They did begin to be seen less frequently after that, thankfully, as their owners woke up to the fact that they really needed something better--almost anything else! Something that would get them through a gig, and then some.
BBE Sonic Maximizers. My bad go-round with one of these was just a few years ago, where one of them is across the mains of a large church sound system. (Their FOH speakers are a quartet of Bose Panarays, and four--count 'em, four--Bose 'Wave Cannons' for subwoofers! Screeching upper mids, ragged highs, and insane, boom-car bass. Their music director is college-educated, so he knows this is the best!) One of the worst sound systems I have ever heard. Suffice it to say, anything that dynamically boosts upper mids and highs has no place in a FOH system. Is there any place one of these sounds good, beyond when it's disconnected?