As far as unknowns go, it happens a lot, but that's part of why we do this kind of testing. One example that I can think of is that Sweethome did a piece on soda makers last winter, and the best choice was not a Sodastream as one might expect. It ended up being the Purefizz by Mastrad, which is a little-known foreign company that typically makes tools for chefs so they can make things like meat-flavored foams and whatnot. They made a carbonation device that creates a better, more fizzy product than the Sodastream, and without proprietary cartridges for the carbonation.
How do you choose which products to test? Specifically I am curious how nail clippers got on the list.
It's a magical combination of what the readers have been requesting from us (and how often), what the Google search terms are telling us, and what we just plain feel like reviewing. Obviously we try to put more weight on things that we're getting a lot of requests for, or that people are searching for on Wirecutter/Sweethome where we don't have anything published yet. One example of that is the aforementioned router piece—we had an old piece that was in desperate need of updating, and we kept seeing more and more requests for it. So now we have someone working on a totally fresh piece that recommends which router to buy. Same thing goes with Sweethome stuff—we're working on this great (but complicated) piece about lotions and moisturizers because we've been getting so many requests to touch on beauty products.
Of course, every so often, we feel tempted to just tackle a subject even if it isn't totally practical, like personal drones (the kind you fly around). We've got a piece on that coming up because the it's a cool topic and the timing was right (in terms of writer availability, and experts willing to talk to us about the topic). Sometimes we just have these amazing pie-in-the-sky ideas that we shelve until the right writer or the right expert comes along. When that happens: magic.
How is this information important for consumers? What sorts of feedback do you get from readers?
Generally speaking, the readers are just absolutely thrilled that we're saving their time by doing all this research for them and presenting it in a transparent, easy to understand way. Our audience on both sites is really diverse: we have a following of techies and foodies (Wirecutter and Sweethome, respectively), but we also have a pretty big following of just regular folks—parents, grandparents, friends, neighbors, etc.—who are just tickled to death that they can get information about stuff they're not experts on so they can just buy it and be done with it. No weeks of research and confusing numbers to compare for them.
In fact, although the readers tell us regularly that they love having all the research and testing data available to them, we find that some readers just trust our process enough to not bother reading the whole reviews. We get tweets all the time from people who say they just look for whatever we recommend at the top and buy it without reading the rest of the guide, because they have so much confidence in our tenacious research. We're really flattered that people do that, but we do like to keep all that information there on the page so those who want to find out how we came to that conclusion can do so.