My worse disappointments:
Lew's tournament pro bait casting reel. I bought first run of the reels. Had to return one immediately. Kept second one, still have it and still plan to make it work. Great reel in many areas on first season of use...now it's just a benched table weight.
Berkly Vanish. I've forgotten why I ever used that in the first place.
Spiderwire Fusion. It makes Fireline look wonderful. LOL yeah the list of tradeoff for Fireline is well you know if you have used it.
Quantum Snapshot open face spinning reels. Love the looks, performance was more reel fighting than fishing. Like the rod for a bit but it snapped.
Cabela's Ripcord SI braid. Flat and gets you more wind knots than you need if it weren't line digging into the spool.
Ugly Duckling lures. I bought a bunch... Never caught anything with it. Tried to fish hard into wood cover but somehow they don't snag either, nor do they wobble at all.
Some pradco lures that never ran correctly. LOL
Rapala skitter prop...why can't I catch a fish with it. Lousy prop that won't turn unless I'm ripping it. Gosh and they still won't bite it on the pause.
Maxima Ultragreen...works great on day one, day two it starts to deform, degrade, whatever wasn't working like day one. Week later, why I am a cheapo and put up with it. Oh well, the saying fresh line is best. I still have my half used filler spools as proof that I actually used it. LOL.