1) Christmas gifts when you don't know what else to buy. (Hey, s/he likes to cook, I'll bet s/he'll love this juicer-coffee maker-corkscrew-hoopa combo!);
2) Taking up that annoying, extra cupboard space in your kitchen; and
3) Filling your spare time with disassembly and reassembly of 15 razor-sharp parts.
That said, I do recommend a select few kitchen gadgets:
1) An ulu. Best. Invention. Ever. Thank you, native Alaskans. Hide-scraping notwithstanding, you have done a wonderful thing for all my slicing and dicing needs.
2) A immersion blender. Think cream soups without the cream, and no dirty blender to assemble, use, disassemble, wash, and reassemble.
3) A microplane zester. How did i zest citrus without this? I also use it for hard cheeses, chocolate, and spices.
4) A bookend. Something has to hold up the cookbooks!
Her name is Souffle. In addition to bookending, she is good for pre-washing the butter dish if we forget to cover it, tripping the cook (particularly while said cook is carrying a saucepan full of marinara), and being too cute to incur the cook's wrath.
Blasted kitchen gadgets.