You've seen ads where you can save "up to 50% or more." The only amount you are guaranteed ''not'' to save, then, is precisely 50% (unless "up to" is inclusive). So basically the ad is saying you could save any amount at all, including nothing.[[note]]In fact, if you see signs proclaiming "up to ''x''% off", the store could actually get away with ''increasing'' the price, as that would be less than ''x''% off the original price.[[/note]] How maddeningly non-specific.
The intent is that "up to 50% or more", instead of being interpreted as "anything", is often interpreted as "most likely 50% with possibilities of taking it to the next level", and thus the advertisers try to get consumers thinking they could save even more than that (i.e. "at least 50% off" without having to ''say'' that and be bound to it). Does this really work? It must, because advertisers (particularly low-budget ones) keep doing it.
A fairly common variant of this now invoked by advertisements for cleaning products is that they kill "Up to 99.9% of bacteria". What this in fact means is that they could kill any quantity of bacteria from none at all up to 99.9% (including 99.9% if they meant "up to" to be inclusive), but they specifically ''won't'' kill all bacteria. Doesn't sound quite so good when you think about it, does it?[[note]]On the other hand, there ''is'' good scientific and legal reason for this, and not half as cynical as thought: they'd very much ''like'' to say that their product kills 100% of bacteria, guaranteed, but thanks to the simple facts of science and truth-in-advertising laws, they can't guarantee that it'll kill ''everything''. However, in most cases, it is true that the vast majority--possibly, in ideal conditions, 100%--of bacteria would be killed by any product making such a claim, as these tend to contain bleaches, alcohol, and other substances which have a ''very'' good--and in the case of alcohol, long (when was the last time you saw [[Series/ArrestedDevelopment a bottle of vodka go bad?]])--track record when it comes to killing microscopic creatures.[[/note]]
A very similar thing happens with beauty products. Anti-dandruff treatments will tout that they will leave your hair "up to 100% flake free". A moment's thought tells you that so will anything else you try, including doing absolutely nothing.
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