Which logical fallacy is used in the text?
According to the commercial, four out of five people surveyed said that they use Twinkle Bright toothpaste, so it must be the best.

 - red herring: the use of a completely unrelated topic or idea
 - bandwagon fallacy: the assumption that the popular choice is automatically correct
The text argues that Twinkle Bright is the best, because many people use it. However, even though lots of people use Twinkle Bright, that doesn't necessarily mean that it's the best. This illustrates a type of logical fallacy known as the bandwagon fallacy.