k1w1k1d: A good example of this is the number of internet routers listed in the power tool category.
That's because that is where TM defaults to putting them, and you need to override it. The even bigger issue though is it automatically restricts searches to the same categories and it isn't obvious it is doing it so ignorant buyers will miss out on many relevant matches. Pick any other marketplace site and they offer some suggested categories to restrict to after displaying your search which means you can get to meaningful results quicker.