If you ask Dame Edna, the Aussie megastar of Broadway and queen of TV cameos, how she got to be so famous, she will tell you that it’s all a great big accident. Fame fell to her, and she grabbed hold of it with mauve-tinted muscle. A few years ago, I saw her Tony Award-winning show on Broadway, and it was one of those theater experiences that leaves you smiling in the way a good musical leaves you humming the songs on your way home. I came away whistling with great admiration for Dame Edna and her creator, Barry Humphries, the man behind all those hues of wisteria and hysteria.

I expected to have a similar reaction to “A Night with Dame Edna” presented by PCA Great Performances at Merrill Hall in Portland over the weekend. The show began as usual with Dame Edna’s entrance in a fanfare of gladiolas, flailing lights and cascading music (played by pianist Wayne Barker), with dancing embellishments by Ednaettes Teri DiGianfelice and Michelle Pampena.

Bejeweled and booming, Edna called out to her cheering fans: “Yes, yes, it really is me tonight! A dream come true: Me, Edna, in Portland! In the little tucked-away Merrill theater!”

With the full and eager complicity of the audience, referred to with affectionate derision as “possums,” Edna launched into her show, which includes vignettes about her gay son Kenny, her trailer-trash daughter Valmai, her late husband Norm and her best friend Madge. The house lights were up as Edna engaged the audience in comments about the misdirection of their fashion choices and probed into home-decorating secrets (or debacles, after she transformed them through her own zealously bespectacled eyes). With delicious abandon, she picked on seniors, on yuppies, on the cheap-ticket section in the balcony and did a running gag on a group she dubbed “the mutes.”

Typically for the repartee, she chooses an audience member and rings up the babysitter to wryly humiliate the employer. On the opening night of her four-show stop in Portland, she called an elderly mother whose daughter had left her at home and ribbed them as a family. She also invited two women in the audience to an onstage meal, which they ate while she shamelessly bombarded them with graphic anecdotes meant to – suffice it to say – curb their appetites.

The bit-filled pastiche was a whirlwind combination of quick wit, audacious raunchiness, scatological humor and the rank self-aggrandizement that comes not only with Dame Edna’s God-given ability to laugh, as she says, “at the misfortunes of others,” but with her lavish costumes of feathers and fringe. And I mean that – for the most part – as a compliment.

After all, that’s what we call entertainment and her following is a testament to real success. It’s not for nothing that some of her lines were lost in the rafters because the audience was so loudly laughing. But as I watched the show this time, I seriously wondered why I ever found it that funny to begin with. I grew impatient and annoyed with her routine because it felt, well, like a tired routine. And there are others out there in the world of comedy – Eddie Izzard, for instance – who step onto the cutting edge and stay there.

It could be that the Portland audience, though generously effusive, gave her less material to work with than her usual gang of gawkers. It could be she was having an off night. But I suspect that the shelf life of Edna is near its expiration date. Or, at least, that it expires quickly – in my case after one show. I don’t mind that she reels you in with humor just long enough to stab you with a hook. I don’t mind her political incorrectness. But I greatly mind not laughing as much as I had planned to.

Does this mean I don’t like Dame Edna? No. I have fond memories of her. And I was, admittedly, amused from time to time at the Portland show. Nevertheless – and running the risk of loneliness – I have to declare myself a possum who has fallen by the wayside.