It was easy to believe that the Diner, which opened several months ago in the restaurantland of Adams Morgan, is not quite what it seems: a greasy spoon wrapped up in a little nostalgic fluff. Cutesy theme restaurants such as the similarly focused Silver Diner and Johnny Rockets have avoided city neighborhoods. And the Diner, which doesn’t fall for the worst excesses of some imitation ’50s burger joints—blessedly, you aren’t forced to listen to “The Wanderer” over and over again courtesy of boothside jukeboxes—is an offshoot of Tryst, the self-consciously suave coffeehouse/bar two doors up 18th Street. Further evidence that the Diner might be up to something different comes from the menu, which includes a few nondiner items, as well as from the young, hip, and pierced crowds that have happily filled the place since it opened.

In this case, however, looks are not deceptive: The Diner is a diner. Ride the irony, baby!

The Diner occupies a huge room, charmingly appointed with a tin ceiling and a tile floor. The long counter that runs along one side is made of tooled steel in a kind of geometric art-deco pattern that speaks to the design sensibilities of the late ’40s as much as the rockin’ ’50s. That shimmering slab of metal, as well as the straight-out-of-Nighthawks coffee urns and fixtures, carries most of the burden for providing atmosphere. Away from the bar, the room is as sparse as the bleakest college cafeteria. Wooden chairs, tables, and booths, so drab as to neither enforce nor clash with the countertop, fill the remainder of the room. The expansive walls are empty.

The menu is a mix of the expected diner food—burgers, sandwiches, meatloaf—and a few more intriguing entrees. However, the kitchen, barely competent in the use of the griddle and the deep-fat fryer, is not up to even the most rudimentary of other cooking tasks. At my first dinner, I was presented with a piece of once-high-quality salmon that had been grilled well past the point of no return. It was served dry and came with sides of nearly raw new potatoes and boiled-limp green beans, neither of which had sauce or butter. It’s a fine meal for a monastic but a little sparse for those of us who have not given up life’s pleasures—and hardly in the guided-by-fat diner tradition. I was surprised that my fish had had time to become so overdone: It was at my table barely after I ordered it, beating the appetizer course of too-gingery vegan carrot soup by a minute.

From the check, I learned that it was my waitress who had decided that I wanted my fish “well done.” Perhaps she knew best, but it probably wouldn’t have mattered even if she had bothered to consult me. A medium-rare burger I ordered on another occasion showed only the faintest hint of pink, and the rosemary chicken comes dried-out, tasting more like cured garlic than rosemary. Vegetables are as likely to be raw—as were the bite-size carrots that came with my meatloaf—as overcooked. The meatloaf itself, doused in flavorless gravy, is nearly inedible, a gelatinous wedge of ketchup-flavored gray meat flecked with carrot.

With a wait staff more interested in yukking up friends among the customers than guiding you through the menu, land mines are unavoidable. My waitress offered to heat the apple pie I had ordered, but she neglected to mention that I would be biting into a half-frozen wedge rather than the room-temperature slice I was expecting if I turned her down. And my post-entree soup was not so much as acknowledged. In general, salads go unpeppered and questions about your culinary happiness go unasked.

But I’m missing the point. The Diner is meant for scenesters, not diners. Open 24 hours, it offers some of the best people-watching in Adams Morgan, and it’s the obvious dining choice in the early hours of the morning, when it’s, well, the only choice. If you do find yourself there, it is possible to win the face-off with your plate, so long as you stick to basics.

The Caesar salad is the typical fake restaurant version but is perfectly edible, with a good mix of crunchy and leafy romaine. The Diner burger is generously sized and usually juicy, if no more flavorful than supermarket ground beef. A friend has a permanent grudge against the place because not one of the three grilled cheese sandwiches he’s ordered has been properly melted, and the same is true of my grilled Gruyère on rye, but the kitchen seems able to handle the basic American-on-white combo.

The onion rings have a nice hard crunch and aren’t greasy, but have little onion flavor. Though I’m usually not a mac-and-cheese fan, I find the Diner’s version pleasant. Even though it blends three hard and tangy cheeses—Parmesan, Gruyère, and cheddar—it’s creamy in texture and understated in flavor, if also a little oily. My favorite sandwich is the grilled portabello, which a companion ordered without the Muenster cheese that normally comes on it. Served on a roll that tastes faintly of sourdough, the earthy mushroom is enlivened by a generous portion of roasted red peppers. And the safest meal—otherwise known as breakfast—is served all day.

Diner desserts are usually not worth the calories. The apple pie is a mushy pile of sweetened, spiced applesauce, served inside a hard, bland crust. The raspberry-peach pie is better—the tartness of the raspberries plays nicely against the sweet peaches, and the fruit seems fresher—although it’s baked between the same unfortunate sheets of cardboard. The most successful dessert is the brownie part of the brownie a la mode, which features the sort of dark, rich chocolate you can get lost in. The ice cream, however, is thin and artificial-tasting.

Of course, artificiality is usually not the problem here. The decades just after World War II are not remembered as a high point of American cuisine—which means that we can at least credit the Diner for being true to its adopted era.

The Diner, 2453 18th St. NW, (202) 232-8800. —Jandos Rothstein

Eatery tips? Hot plates? Send suggestions to hungry@washcp.com. Or call (202) 332-2100, x322.