From
http://www.thefreedictionary.com/fulsome
Usage Note: Fulsome is often used to mean "offensively flattering or insincere." But the word is also used, particularly in the expression fulsome praise, to mean simply "abundant," without any implication of excess or insincerity. This usage is etymologically justified but may invite misunderstandings in contexts in which a deprecatory interpretation could be made. The sentence I offer you my most fulsome apologies may raise an eyebrow, where the use of an adjective like full or abundant would leave no room for doubt as to the sincerity of the speaker's intentions.