Question: If "reek" is used as a term to describe something that smells bad, what word of equivalent meaning would describe something that tastes bad?

Answer: 
Perhaps "**smack**" would serve. This meaning of the word is defined by [oxforddictionaries.com](https://en.oxforddictionaries.com/definition/smack) as

> 
> Have a flavour of; taste of
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and 

> 
> Suggest the presence or effects of (something wrong or unpleasant)
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**Bite**. Often implies acidity, but works for any strong flavor.

> 
> 3A sharp or pungent flavour. ‘a fresh, lemony bite’
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ODO bite: <https://en.oxforddictionaries.com/definition/bite>