They say sex sells in advertising, but apparently, Daddy changing a diaper can also lead to big bucks.

Fathers are watching the little tykes without Mom around in ads for carpeting, department stores, nasal spray, wireless technology, cereal and other products — a move that experts say reflects the modern family.

"More and more fathers are engaged in child care and purchasing patterns that used to be the exclusive decisions of women in the household," said Peggy Conlon, president and CEO of The Advertising Council (search), which conducts ad campaigns for public awareness. "We see it play out in the actual advertising itself."

While most people are happy to see dads starring in more TV ads, there's controversy going on behind the scenes about how they're being portrayed.

Fatherhood rights' groups complain that more often than not, the TV ad Dad is just a big clown who can't handle parenthood without his very together mate, Mom.

"There's still this myth of dads falling into the ‘3Ds' — Dumb, Dangerous or Disaffected," said Vincent DiCaro, spokesman for The National Fatherhood Initiative (search), one of the big daddies among such advocacy organizations.

Among the companies that have taken heat for their Dad ads is Verizon, for a commercial that shows a father helping his young daughter with her homework until Mom comes in, sees the exasperated look on the girl's face and tells her husband, "Tom, leave her alone."

A Wyeth FluMist nasal spray ad featuring a mother sick in bed while a father fumbles through getting the kids ready — eventually sending them out in winter weather with summer clothes on — also came under some fire.

And JCPenney got e-mails — mostly from a fathers' rights advocate, according to Penney spokesman Tim Lyons — critical of a commercial in which a mother shops happily at a Penney's sale while the father stays home trying to feed their unruly baby. At one stage, Dad asks the child, "When will your mother be home?"

But the advertisers — many of whom are fathers themselves — don't see a problem with any of the Mr. Mom ads.

"I don't think there's a campaign out there trying to depict fathers as useless," said Gary Johnston, global brand manager for Stainmaster Brands — which has an ad showing a dad wrangling with a fussy infant until the soft Stainmaster carpet lulls the babe to sleep.

JCPenney's Lyons agreed, saying his company's "When will your mother be home?" commercial was meant to be light and funny — and was aimed primarily at women, since about 80 percent of the department store's purchases are made by female buyers.

"It's something men and women can relate to," Lyons said of the ad. "Dad is home taking care of the kids. He may express frustration, but it's done in a lighthearted way. As a father, I could see a little of myself in that spot, taking care of small kids when my wife is away. It's challenging, but you deal with it. When I first saw that spot, I laughed."

Other dad's-in-charge commercials have similar strategies in mind, with the modern and presumably more domestic father as a secondary audience and the lady (and primary purchaser) of the house as the main target. After all, women tend to find men with babies sexy.

"What we're trying to do is appeal to women, that 25-plus audience, [and show] it's safe to leave them on their own," Johnston said. "They might have a few problems but … Dad can handle it, and if he's got a Stainmaster carpet in the house, he has a little extra help."

The portrayal of fathers on television, in both ads and entertainment programming ("Everybody Loves Raymond, "Yes, Dear" and others have gotten flak in the latter category) has recently been a hot topic of discussion in political and media circles.

Last month, The Advertising Council and The National Fatherhood Initiative announced they were launching their latest public service announcements encouraging more fatherly involvement with the kids.

The new PSAs, airing soon with actor Tom Selleck (search) doing the voiceover, conclude with the tagline, "It takes a man to be a dad." One features a father dancing with his daughter in the living room and, according to the Advertising Council's Conlon, tries to speak "directly to fathers of the importance of being engaged in their children's lives."

And while fatherhood activists are grumbling about some of the ads they see as daddy mockery, they're also taking note of what they call "father-friendly" commercials.

The NFI names a handful of companies each year that it believes demonstrate such positive marketing. Cheerios, Marriott and New York Life were among the television winners last year; this year's TV nominees include Kraft Singles for a heartstrings-tugging spot about a dad helping his little girl make a grilled-cheese sandwich.

Daddies themselves have had a mixed reaction to seeing themselves portrayed more domestically in ads. Some aren't fazed by any of the commercials, even the dopey dad ones, and think the offended parties are overreacting. Others are happy to see that some ads have moved away from painting them as comically clueless.

"I think it's a very positive development that Madison Avenue [known for advertising] is trying to portray fathers as real people instead of bumbling stereotypes," said USA Today media reporter Michael McCarthy, the father of two tots. "Dads need all the support they can get these days."