When I "worked for the man" I wrote some code that did that logged all searches with zero results. After building up bit of data we did one of two things. Some searches we automatically redirected to the right terms for example [garbage cans] got redirected to [waste receptacles]. The merchants refused to change the name to [garbage cans] insisting they didn't sell "garbage". The second was having a database of likely possible other matches. For example customers searched for [dishes] and the merchant called it [formal dinnerware] and [casual dinnerware]. So the customer got something like
It takes a lot of time and is really going to "hurt" in the beginning but you can improve things and hopefully learn a bit in the process.