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. 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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