Hollywood starts each TV season with the assumption that sex sells, and it's hard to say it doesn't when almost every show harps on sexual themes like an addled assembly line. Some succeed, some fail, and the ubiquity of sex makes it hard to determine whether sexed-up plotlines play a role.

The academic question for this fall season's premiering shows is: When raunchy shows fail, can the blame be placed on factors like bad acting, bad writing, bad scheduling, bad luck? Or do raunchy shows fail because of ... raunch?

Two of the biggest surprises to network programmers are the dismal ratings performance of NBC's "Coupling," the even more crotch-obsessed cloning of "Friends," and Fox's "Skin," the drama strategically situated in the pornography business.

The "Coupling" ratings have been so bad on Thursday nights just before the aging "E.R." that it's ruining NBC's hold on the key young-adult demographics and is threatening NBC's overall dominance on Thursdays. It's no wonder Jeff Zucker and other frightened Peacock Network geniuses rushed to put the show on "hiatus" for the November sweeps.

Critics were highly skeptical from the beginning about this show, which seemed to be an attempt to reproduce a BBC reproduction of "Friends." Viewers have been assaulted by the crass, artless series that never seems to roll out of the bedroom. The focus is not so much on sexual acts as on non-stop sexual chatter. Remove that, and there's no show. Its contribution to Western civilization is lines like this: "Oh, my God, I bought myself a small-penis car! I don't have a small penis. My car's a liar!"

In the series premiere, a male character explains the concept of how a friend and he are "porn buddies," and that if one friend dies, the other will go over to his place, clean out the porn collection and get to keep it. But that's classy compared to another episode, where two of the males get embarrassing erections at a funeral -- that's right, at a funeral -- and try to keep undertakers from moving the casket to avoid being discovered. Isn't that a recipe for giggles a-plenty? The "humor" comes when the undertaker asks if they'd like to get a last look inside the casket, and one says, "That ought to do the trick."

Proud NBC has become pathetic.

And then there's Fox's "Skin," the newest project from Jerry Bruckheimer, the maker of the hot (but often sleazy) crime show "CSI." It opened to a warmer critical reception, with some cultural observers licking their chops at "cultural Puritanism" taking yet another hit. Months before the premiere, New York Times boor Frank Rich was giddy at "the prospect that (actor) Ron Silver's porn mogul may turn out to be more principled than (actor) Kevin Anderson's self-righteous lawman." He added: "Bruckheimer didn't get where he is by being ahead of the curve. He is the curve. His gut tells him, accurately, that porn is not just well within the American mainstream but overdue to be stripped of its plain brown wrapper in prime time."

Melding prosecutors and pornographers into a "sophisticated" shade of gray is an easy way to win over the amoralists. The porn mogul is a warm, fuzzy daddy so principled that he would not get involved in child pornography (a round of applause here?). The prosecutor, on the other hand, is a hyper-ambitious, adulterous jerk, and a faulty parent to boot. Critics hail the breaking of "television pieties" -- as if piety belonged in the same sentence as television.

Rather than complain that the show's premise is manipulated straight into the national zipper, critics were more likely to react by saying the show wasn't sex-drenched enough . In Time, James Poniewozik complained the porn business seems to be portrayed as too disreputable and is not properly honored for its attractiveness to millions of males: "'Skin' does an admirable job of showing us the politics, the culture, the angst of sex. Would the sexiness of sex be too much to ask for?"

The poor ratings were puzzled over, but mostly based on sports arguments. Did the premiere of "Skin" within Fox's nearly nightly baseball playoff lineup hurt the show? Can a porn-based show attract an audience against "Monday Night Football," since many men are busy and not as many women would seem to form the majority of that so-called massive, all-American, porn-loving caucus?

Hopefully, the woeful ratings of crass shows like "Coupling" and "Skin" will show network executives that Americans aren't simpletons fixated on sophomoric sexual titillation.