headliners and regular cloth (seats and such) are 2 totally different things. Even if a products is safe and effective on seats does not mean you should use it on the headliner. wetting the headliner can cause the adhesive to fail and it can start sagging. IMO choose a VERY mild cleaner and a lightly damp cloth and lightly rub the headliner. be careful not to saturate the headliner and you shouldn't spray any cleaner directly on it. For basic cloth seats, a mild solution of a carpet / upholstery cleaner (or some use woolite and water 6-10:1) should work for general cleaning and light stains.
Eric