While Bette may not disappear in the role, it's a perfect example of when artist and role blend beautifully. Bette herself is not the Divine Miss M-that's also acting. So when people see familiar mannerisms it's Bette acting. Even if they think they are just seeing Bette herself, they aren't. They are seeing her craft. That's why it bothers me when reviewers say she is just being herself on stage. Uh, hello, she is not. That's not her. She's wildly talented but pretty low key in her day to day.
Now as for Dolly. When Dolly is cast, she is cast as Dolly. She alters nothing about herself-her hair, make-up, clothes or her speaking voice. You're hiring the package. You can't have a Southern Dolly Levi. She killed the Mae West project because she'd have to alter her speaking voice and wear short wigs (which Dolly dont like or do). Dolly likes total creative control and taking over for Bette would probably not appeal to her.
"The sexual energy between the mother and son really concerns me!"-random woman behind me at Next to Normal
"I want to meet him after and bang him!"-random woman who exposed her breasts at Rock of Ages, referring to James Carpinello