It may be that unexpected contacts appear on your list because the AND vs. OR logic was used incorrectly in the list criteria
- Navigate: Contacts > Lists
- Select List in question and edit the criteria
- Ensure that the logic for AND vs. OR is correct.
- Using the AND logic means contacts will need to meet all criteria within that set
- Using the OR logic means contacts will need to meet at least one criteria or the other criteria
Example using And... criteria:
Example using Or... criteria:
You can also use the "Test contact against this list" option to see if a specific contact meets any of the sets of requirements you have in your list logic.