Basses I've tried that disappointed me?
Warwick Thumb - Neck was too chunky. It was like holding a baseball bat that had been halved & fretted. The bass was way too heavy for how small the dimensions are.
Ernie Ball Music Man - Don't get me wrong, I love the tone, but I hate how they feel. The necks are inconsistent & remind me of clubs.
Ibanez SR 5-strings - I've played probably about 20-30 of these, from the SR305 to the high end Prestige models of varying years. The low B has always been floppy, to me, and the lack of any body weight can lead to limited low-end resonance on some of the lower cost models.
Gibson EB-0 - IMO, short-scale basses are for guitar players who want to play bass. Or for people with REALLY tiny hands. I'm also not a fan of the mudbucker, or minibucker.
Sadowsky J-bass - Played 2 or 3 of these. I'd buy a Fender American for less & be happier.
Dingwall 5 strings - As a guy who likes to stay in the low range, that 36" scale on the Low B is just too much of a stretch from fret 1 to 4. Also, the "truer" intonation sounds off to my ear. That is probably just from years of playing traditionally fretted instruments.
Rickenbackers - Butt ugly.
Spector Performer Series - They feel like an Ibanez GIO, but at 2-3x the cost. Quite the let down.
"Beatle" Violin-style Basses - Someone, PLEASE steal the DeLorean or TARDIS, go back in time and prevent McCartney from ever picking one of these up! They're always poor build quality, junk tone & over-priced nostalgia pieces.
Anyways, in retrospect, most of my disappointments are all due to taste (except with the Violin bass). I'd assume that everyone else is the same way.