LAS VEGAS — The problem with Miley Cyrus isn’t that she has broken bad. It’s that she’s so confusing.

One day, she’s sexualizing herself without actually being sexy, putting her hair up in double buns like a baby devil’s stubby horns and sticking her tongue out like a cartoon-character Calvin making faces at his stuffed tiger.

The next, it seems, she’s singing Wrecking Ball, a devastating piece of heartbreak pop that ranks among the year’s very finest singles.

If she’s trying to show how grown up she is by how lewdly she can act, she’s not doing a very good job of it.

At the same time, conventional wisdom suggests that rubbing foam fingers in places foam fingers ought not go doesn’t help her credibility as a singer of serious fare like Wrecking Ball. Perhaps, as proposed by Elton John — who, like Cyrus, played this weekend’s iHeartRadio Music Festival in Las Vegas — she’s a “meltdown waiting to happen.” Frankly, it’s hard to tell.

What’s great about Miley Cyrus, though, is that she’s so funny. She has a weird and finely tuned sense of humor, which she displayed Saturday during two performances at the festival, particularly her afternoon set at the Music Festival Village.

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Dressed in a white hot-pants suit with laces that went flying every time she swiveled her hips toward the audience, Cyrus performed We Can’t Stop and Party in the U.S.A. while surrounded by dancers wearing inflatable mushrooms and rainbows, as well as twerking little people. The colorfully absurd stage looked like a cross between a Super Mario Bros. video game and a demented early-’70s children’s television show.

With all Cyrus’ activity the past few weeks — her performance at the MTV Video Music Awards, appearing naked in her Wrecking Ball video, breaking up with Liam Hemsworth — she’s shown an uncanny ability to astonish. But Cyrus could hardly have come up with anything more flat-out flabbergasting Saturday than one of her song choices — Look What They’ve Done to My Song, Ma.