The Maitlands' "powers" in Beetlejuice

Question

Early on in Beetlejuice, Adam and Barbara perform some scare tactics - a beheading and a gruesome face removal. No one notices.

Shortly after they go to see Juno (their 'caseworker'), who says:

It obviously doesn't do any good to pull your heads off in front of people if they can't see you.

Later they go to see Juno again and show her their grotesque monster faces. She is pleased and praises them for their ability to be scary.

What has changed? How did they suddenly gain full "ghost powers"?

Despite doing essentially the same thing as they did in the beginning - for which they were admonished - there is now at least the presumption that they'll be able to scare the Deetzes.

Unless I missed the explanation, this seems like a pretty big plot hole.

Answer 1

Juno explains to them at their first visit that they have to study from the manual and practice. "It obviously doesn't do any good to pull your heads off in front of people if they can't see you" speech happens in this dialogue. So they start to do it. Here is the conversation between them:

Juno: I'd almost given up on you. I was about to leave. I do have other clients.

Barbara: Are you Juno, our caseworker?

Juno: Yes. I evaluate individual cases and determine if help is needed, deserved and available.

Adam: Are you available?

Juno: No. What's wrong?

Barbara: We're very unhappy.

Juno: What did you expect? You're dead.

Adam: We want to get rid of the people who moved in here. Barbara and I worked very hard on this house.

Barbara: We probably wouldn't mind sharing the house with people who were...

Juno: More like you used to be.

Barbara: Yes.

Adam: But these people...

Juno: Things seem pretty quiet here. You should thank God you didn't die in Italy. The Deetzes. Okay, have you been studying the manual?

Adam: Well, we tried.

Juno: The intermediate interface chapter on haunting says it all. Get them out yourselves. It's your house. Haunted houses aren't easy to come by.

Barbara: Well, we don't quite get it.

Juno: I heard. Tore your faces right off. It obviously doesn't do any good to pull your heads off in front of people if they can't see you.

Adam: We should start more simply?

Juno: Start simply. Do what you know. Use your talents. Practice. You should have been studying those lessons since day one.