In addition to the other answers, keep in mind whether the question is worth answering at all. This style of question can quickly veer into really lame, boring, uninteresting questions:
Does milk sold in grocery stores actually come from cows?
Do AA batteries fit in appliances expecting AA batteries?
Do vacuum cleaners work?
Some questions of this form are awesome and interesting — I actually think the vacuum question could survive — but a question isn't suitable just because the form is valid. When comparing two products to each other you still need an interesting comparison or claim.
Does Ivory soap clean better than Dove?
Do more dentists actually recommend toothpaste brand X?
Even aside from all of the ambiguity and subjectiveness of terms like "better" and "recommend", questions of this form are not inherently interesting. Some of them could be, sure, but I don't think the general case of comparing brand effectiveness is a very interesting topic.