hmm, interesting. I didn't find them monstrous, just vacuous and confused.
Was just reading Ebert's
re-review, and found this bit interesting:
"The famous opening scene, as a statue of Christ is carried above Rome by a helicopter, is matched with the close, in which fisherman on the beach find a sea monster in their nets. Two Christ symbols: the statue "beautiful'' but false, the fish "ugly'' but real. During both scenes there are failures of communication. The helicopter circles as Marcello tries to get the phone numbers of three sunbathing beauties. At the end, across a beach, he sees the shy girl he met one day when he went to the country in search of peace to write his novel. She makes typing motions to remind him, but he does not remember, shrugs, and turns away."
Not only is the symbol of Christ more "real" in the ending scene, the girl Marcello fails to communicate with is too. Marcello begins as a man idolizing false gods, with his perceived sweet life just out of reach. In the end, he's living that life, but no closer to happiness, and a genuine sweet life is further out of reach.