Ingratiatingly tells you how someone did a thing: they smiled, spoke, or behaved in that too-eager-to-please way. The disapproval sits in the word. He laughed ingratiatingly does not mean he laughed because something was funny; it means the laugh was for the other person’s benefit, to be liked. It is not a word you need in everyday chat; it turns up in stories and in slightly formal writing when the writer wants you to notice the act.