God, we sound just like them,” said my colleague.

By “them,” he meant malicious Lady Sneerwell, dotty Mrs. Candour, wicked Sir Benjamin Backbite, and the other ­reputation-ruiners in Richard Brinsley Sheridan’s The School for Scandal, a highly mannered comedy of slander among the late-18th-century smart set. And he was right: We were taking the Folger Theatre’s new production apart, and it was barely intermission.

Don’t get us wrong, we’re fond of the play. It’s a wickedly entertaining thing, all about a one-time country girl (the mischievous Lady Teazle, played by Kate Eastwood Norris) who’s married well and fallen in with a fast crowd, finding herself dangerously amused by their gossipy citified ways. Sheridan serves up plenty of lively spousal banter for Lady T. and her put-upon husband (David Sabin’s Sir Peter), plus a nicely knotty rich-uncle’s-legacy plot involving the upright Joseph Surface and his black-sheep brother Charles. (Neither, as their surname suggests, is quite what he seems.) Oh, and there are no fewer than three star-crossed courtships—or at least potential dalliances—of which to keep track, which means at least six reputations hang on the outcome. Delicious.

And it’s not the performers we regret—most of them, anyway. Norris is one of the town’s most reliable comedians, Sabin one of its savviest old hands. Catherine Flye, this School’s speech-impaired Candour, could play that beldam’s befuddled nonsense in her sleep, and Hugh Nees’ ear-steaming slow burns (he’s the rich uncle, come in disguise to assess his nephews’ inheritance-worthiness) have rarely been put to better use.

But what is the usually canny actor Tom Story doing, straining Lady Sneerwell’s stays so manfully? Why is Backbite (young Nathaniel Claridad) performing as though his character is called Overbite? For that matter, why is half the rest of the cast—ensconced at the Folger’s cozy Elizabethan Theatre, let’s remember—playing broadly enough to sell Sheridan’s witticisms to the nosebleeders at the Verizon Center? Why, in short, does Richard Clifford’s staging, with its unusually muscular villainess, its 1890s setting, its green-carnationed dandies, and its other unharmonized innovations, feel so forced, so labored, so many other strenuous things a comedy oughtn’t be?

Mere size is only part of the trouble. The cast is plainly under-rehearsed, with more than one player fluffing about anxiously in the general vicinity of what ought to be a tart retort. The sets, usually a winning element in any Folger show with Tony Cisek’s name in the credits, look surprisingly chintzy, not to mention half-thought-out: There’s a famous hiding-behind-screens scene involving a half-concealed petticoat, but the screens here do their work so well that I couldn’t spy a slipper, much less a frill.

But mostly, Clifford’s conceit is a cipher, and his direction is so muddled as to seem downright half-baked. If you’re going to cross-cast The School for Scandal—a comedy about how the well-heeled hide all manner of perversions behind their polite surfaces, in a society where the surfaces are crucial and an ill-timed glimpse behind them ruinous—you’ll need to be clear about whether Lady Sneerwell is a woman being played by a man in your production or a man trying to pass as a woman in the world of the play. (And if you’re going for the latter, you’ll need to clue the audience in on whether her social circle has noticed her 5-o’clock shadow and her manly sprint.) Clifford seems content to leave the question open, at least until a half-hearted gesture that offers no real payoff—and that comes in any case too late, attached as it is to a bit of matrimonially flavored sarcasm just before the final curtain.

Sad, that: The School for Scandal is all about passing and pretense, mischief and manners and the mistakes real people make in the landscape between the two. A shift to Oscar Wilde’s era, mashed up with a bit of high-society role-playing, might have promised genius—if only this production’s manner, as Lady S. says cuttingly of a rival, weren’t so gross.