Do not indicate more precision for an event than is stated or clearly implied in the record. Doing so may at the very least be incorrect and at the very worst, be incorrect and lead you down the wrong path. If a marriage record only indicates the county in which the marriage took place, then only record the county. The marriage may not have taken place where you "think" it did. Remember, if you were present at an 1850 wedding, then you know where it took place.
If information allows you to infer (with reasonable certainty) a more precise location, then your notes should include that discussion.