Betti became famous for portraying bizarre, grotesque, eccentric, unstable or maniacal roles, like Regina in Bernardo Bertolucci's 1900, Anna the medium in Twitch of the Death Nerve, Giovanna la pazza in Woman Buried Alive, hysterical Rita Zigai in Sbatti il mostro in prima pagina, Therese in Private Vices, Public Virtues, Emilia the servant in Pier Paolo Pasolini's Teorema, and Mildred the protagonist's wife in Mario Bava's Hatchet for the Honeymoon