The canonical example of "weasel words" is this line you've been hearing in toothpaste commercials all your life: "Nothing gets your teeth cleaner!" Sometimes they even say that clinical studies show this.
Of course the true results of the studies, done decades ago and never repudiated, is that all the toothpastes were equal in effectiveness. Of course the advertisers don't want to say "exactly as good as all the other brands, even the cheaper ones", so instead they say something that sounds like it means their brand is the best, but doesn't really mean that.
My father liked to make fun of this by saying "Hmm, if nothing gets your teeth cleaner, that's what we should use, nothing!" As it turns out, the joke's on him, as well as on the toothpaste manufacturers. Dry brushing (without toothpaste or even water) turns out to be more effective than toothpaste for your dental health. (Though most people still use toothpaste for that clean feeling.) So by trying to deceive us, the toothpaste manufacturers accidentally have been telling us the literal truth all these years.