I'll often find myself reading through various recipes and wondering whether some of the steps, time estimations, etc. are actually correct. Those who write recipes hold a somewhat daunting responsibility to give readers instructions and also, at times, to anticipate questions and clarify explanations. That being said, there are some phrases that are, in some measure, ingrained in our cooking vocabulary and that, even though they may not be completely accurate, we continue to use such expressions.
One of these is the directive to rinse rice (often three or four times) "until the water is (or runs) clear." While the water in this situation will become decidedly less murky, it will likely never rinse completely clear, or certainly not in the 3 or 4 times of rinsing that are suggested.
While really a seemingly small (and somewhat inconsequential) aspect of a recipe, including instructions like this does somewhat test the trust between the recipe reader and writer.
I would be interested to hear others' opinions and examples of similar phrases we use!