I can think of a lot of vacs that I'm not fond of for one reason or another, so I'll pick one that really stands out in my mind as a disappointment.
Sorry I can't come up with more details, but this was 36 years ago and I just wasn't into such things in any great depth.
When my wife and I got married in 1974, we basically started out life with nothing. Our first rented house was furnished literally with cast-offs from relatives and so on. My wife was 18 years old, and one day went down to Repp & Mott, the dirt-bag auction house in our home town of the time and bought some chairs and a table for $5. That sort of thing.
For wedding presents, we had been given the usual stuff, some useful, others obviously re-gifted and useless. One present was a $50 gift certificate for Sears and Roebuck. That was a biggie at the time. Since we needed a vacuum cleaner, we decided to use the certificate to get one at Sears. We went to their local store and picked out an upright vac, which I don't remember much about but the nozzle assy. was plastic and sheet metal, sheet metal pole handle and a bag with little dot holes in it. Since this was the 70's, it was in yellow and light green pastel colors with some white. As I recall, it used up most if not all of the $50. I lasted less than a year. It just kinda fell apart with normal use. I don't think it came with any kind of accessories, it was just a floor vac and if you wanted to do around the edges, well, get a whisk broom.
To replace the sadly and prematurely lost Sears machine, I used a lesson from family experience. My dad's mother had left behind a Kirby Model 510 when she died in 1958 and my mother has used it ever since. Still has it, but with the usual bag, cord, and wheel replacement over time. Anyway, I figured that if this had been a good machine, I'd get one like it. I went to a local vac shop and bought a used Kirby Model 511 and we had it for over 25 years before it needed replacement.