Madstad Adjustable Windshield: Thought it was great until I rode without the shield and with just the mounting plate. Much prefer riding without any kind of windshield at all.
Cheap Tractor Supply Auxiliary Light: Damned thing broke every time I laid the bike down. Decided chances of my headlights failing are actually pretty slim, which is why I had it on there because I ride at night a lot. I figure my LED flashlight from work held in one hand would allow me to limp home at low speeds, illegally, if the need arose.
Walmart ATV Seat Cover: Don't ride long-enough distances to see a benefit from it. It soaked up water when it rained. I like the way my canvas pants tend to adhere to the stock seat cover. I stay where I sit and I don't slide around or back and forth.
Sweet Cheeks Seat "Pad"- Same as above.
Kaoko Throttle Lock: Even when riding longer distances, my ass always got sore long before my right wrist did.
Wolfman Tank Bag: These things shouldn't be called tank bags, they should be called "crotch warmers." Never liked having the thing on the tank. It was handy on one long trip, but I sold it.
Happy Trails Nerf Bar Soft Bags: Never liked having the things sticking out in front of my legs. I still use one on my side guards to carry spare inner tubes and tire tools.