For over a year, we tested the theory that a restaurant is only as good as its restroom by scouring the city for notable loos, ranking them with the unforgiving rigor of our five-star rating system. Always searching for the straight poop, we visited certain facilities months before their restaurants had even opened (“I didn’t know you lurked around toilets,” Park Chinois’ dismayed publicist told us), and fell in love with old favorites all over again. In these dark rooms we found jack-o-lanterns, volumes of existentialist literature, live fish, warnings against cocaine peddling, waterfalls, pachinko machines, S&M gear, and the city’s most expensive toilet. The only thing we missed was Larry Craig. We hope you enjoy the resulting compendium of loos you can use. Please put your own recommendations in the comments.

Rancho Jubilee’s restrooms aren’t the only cave-themed ones. There are La Caverna’s, for instance. But for swankier digs, it’s necessary to visit Ninja. The theme restaurant’s menu is sometimes unsuccessfully derivative — the black cod doesn’t measure up to Nobu’s a few doors down — but when we discovered they’ve recently installed an automatic Toto toilet in the handicap WC, we didn’t give two shits that Morimoto did it first. These actually work!

It’s no secret that wd~50’s bathrooms are as byzantine as its food. Even The New Yorker’s reviewer Kevin Conley wasn’t smart enough to figure them out: “It can take minutes to realize that you have to push the wall — a Mensa-test experience so disconcerting that one diner wound up down the hall in a storeroom.” Having seen our share of hidden doors (Pukk and 44, for starters), we knew we’d be okay when we went downstairs to confront the beast.

If you’ve been to Rancho Jubilee, the totally coco-loco Dominican restaurant in the wilds of Elmhurst that’s fashioned after an over-the-top beach hut (thatch roofing, cavelike plaster ceilings, stuffed turkeys and roosters, waiters in tropical shirts), it’s probably because you had five hours to kill before a flight out of La Guardia a few blocks away and you thought you might as well spend it drinking tequila from a coconut, and then a pineapple, and then a cantaloupe, and then a flaming volcano. Does it beat drinking at the airport bar? Oh, yes. And do the bathrooms beat the ones near Gate 14? Claro que si, papi!

Some things are sacred, and old-fashioned urinals are one of them. Unfortunately, outside of ones that are imported from France, the pickings are slim: You have the ones at Old Town Bar, McSorley’s, and Foley’s (the latter were lifted from the Waldorf-Astoria), but are you really going to eat at those places? When we want a nibble and a dribble, we go for a burger at one of Nat King Cole’s favorite spots, P.J. Clarke’s.

Last week we took a trip to the Far East to hit the loos at Sapa. Now let’s travel even farther east and a little bit north (Madison Avenue at 55th Street!) to Tao, an eatery that’s so authentically Pan-Asian it boasts an enormous Buddha. But then again, so does every other restaurant in town. So how is Tao to distinguish itself from Megu, Buddakan, Buddha Bar, and the rest of them? Via its restrooms, of course!

If you’re one of the swarms of Marc Jacobs–toting girls who flood into Sapa like a Vietnamese monsoon after a long day of arranging “desk-sides,” you already know this, but the place has a great happy hour from 5 p.m. to 7:30 p.m.: $5 specialty cocktails and martinis (and generous ones at that) mean you’ll be sloshed by nightfall. So be careful not to topple over in those Jimmy Choos when you descend the steps, flanked by gauze-covered lightbulbs, into the restrooms.

Consonant rhyme isn’t the only thing Bette and Butter have in common: They’re both owned by impresarios known to cater to the Olsen twins (Amy Sacco and Richie Akiva, respectively); they both have organic, clubby interiors with big murals; and let’s face it, they’re both frequented by the sort of night creatures who know the value of a nice, private bathroom. So just how are those powder rooms?

Before Morimoto, before Buddakan, before Buddha Bar, before Megu Midtown, there was — well — Megu. Sure its star has faded (there was that sexual-harassment suit and such), but no one can argue that the $6 million interior isn't still fresh — just like the toro tartare! Look at the mirrored diorama, outside the restroom, that reflects an Oriental lamp and a flower display into infinity: Way cooler than Morimoto’s mirror installation, right? But what about the rest of the restrooms?

Last week we noted that the once cutting-edge bathrooms of Brasserie were looking quite dull, but on the other side of 53rd Street is MoMA, a place that cultivates the sort of modernism that stands the test of time. Just step into the sexy lighting of the restrooms tucked behind the giant photomural in its ever-elegant eatery, the Modern.