Here's another fun fact about how commerce search engines work (I spent a couple of years on this): Negations sidestep almost all of the algorithms that try to

Here's another fun fact about how commerce search engines work (I spent a couple of years on this): Negations sidestep almost all of the algorithms that try to provide an improved result set, and fall through to pure text relevancy. So try searching on amazon for shirt, then search for: shirt -xkxkxkxk. Since xkxkxkxk doesn't match any documents, the negation should have no effect, but it does, the effect it has is to sidestep all the fancy relevancy work and hardcoded query rewrite rules, domcat rules, demand and sales/impression statistics etcetc, and give you basically awful search results. You don't even get shirts.