@Jamie, looking at your comment below your question, which clarifies your question, the answer would be no not for certain.
An English speaker might be rather familiar with a phrase, and the English speaker might use it regularly, as well knowing other people who also use it, but that doesn't give conclusive proof as to the correctness of a phrase. The factors that affect this include the fact that the phrase might be used in a certain way that as peculiar to the region from which the English speaker came from, and not necessarily applicable to the rest of the world. Also, the "other people" that the English speaker knows might be restricted to his friends and family, who could possibly have been influenced by himself( quite possible).
So, no, not for certain. Just because a native English speaker says he knows it quite well, is not proof for the correctness of a phrase. Without the evidence of a conclusive agreement by the world on such a phrase (such as dictionaries, etymologies, or links), just an opinion is not enough.