Strongly negative.
献 means 'to offer up' (like a gift) and
媚 means 'to charm / flatter' — together it paints someone debasing themselves to please a superior. Use it to criticize, never to describe healthy politeness. Compare
拍马屁 pāi mǎpì (slangier) or
阿谀奉承 ēyú-fèngchéng (more literary).