So many to choose from, I'm sure you might have a favorite. Mine is the 70's "hot dogger" that would electrocute hotdogs between electrodes.
The $1 "paring knife" from a Pampered Chef party. My fingernails are stiffer than its blade.
Hah! Mine is actually very similar to you Sam - I was once given a Mistral Hot Diggity Dog machine, which is evidently only found in Australia:
Complete with bun warming spikes!
Those are vital for making "Puka Dogs" (referring to the shells found in Hawaii). http://toasteroveninus.blogspot.com/2012/07/home-pride-ballpark-hot-dog-rotisserie.html
There's a chain of "puka dog" places in Hawaii where the buns are Hawaiian bread, and spiked and toasted on the spikes and filled with hot dog and other things like Mango sauces.
Last Christmas my mother gave me an electric egg cooker. It hard boils eggs "perfectly in 7 minutes." My kids enjoyed it for a couple of days but now it just takes up space in the pantry. Thanks Sam, you've reminded me I need to drop it off at the thrift store!
This is more tool than appliance, but someone gave me an OXO corn stripper. It leaves about half the kernels behind. A sharp knife works so much better.
My friends mom had the plate where you bang frozen meat on to 'activate' it and it thaws faster. What a pointless invention
I was given a Quesadilla maker. It is like a panini press or waffle iron. Put the stuffed tortillas between them and press. It is a perfect garage sale item. A flat top or skillet works just fine.
My old roomate knew that worthless, space taking kitchen appliances are the bane of my existence. So, he thought it would be hilarious to gift me a quesadilla maker for my wedding. it was promptly returned to the store. At least he was nice enough to include the gift receipt.
Not too set on gadgets...The only useless thing in our kitchen was once a microwave.When it broke we never fixed it and gave it away.We only used it to reheat (or recycle,as a friend says) left overs and coffee,make pop corn,and melt chocolate.Can't think of anything to do in a microwave that would not be better made in another way.
A crepe maker
The Food52 staff had some good giggles over the "Pasta Express" the other week:
In my family, we still use "Ginsu" to describe anything of questionable provenance or performance. ("Thanks for loaning me your power washer - totally Ginsu.") I don't know if they sold decent knives or not. But everyone knows the early infomercial marketing techniques were hilarious.