The stronger the stench, the sweeter the opportunity. As absurd as that notion may seem, it can pay off handsomely for investors in disruptive technologies. Behind every great growth stock, there's a company that approached an old problem in a new way. The earlier you buy into the market's realization process, the greater the gains.

Our Motley Fool Rule Breakers newsletter service specializes in scoring these kinds of big gains. I urge you to take that winning strategy a few rungs deeper into the discovery process by rifling through the ugliest of sectors to find the next batch of market winners. You see, the industries that most need saving are the ones most likely to develop saviors that have the most to gain -- and the most to prove. That only makes it easier for you to fish for them in the cesspools most investors avoid. Last year, I showed you the five ideas I found in ugly sectors. Today, I'll show you four more.

True Religion (NASDAQ:TRLG) is into denim. Even though apparel is a fickle niche and designer jeans feel so 1980s, True Religion's high-end wear is a hit with celebrities and shoppers with disposable income to spare. Last week, the company posted fiscal fourth-quarter results that saw sales surge 88% higher, as earnings soared 83%. That kind of growth rarely goes unnoticed in the market. Yet even though True Religion shares have appreciated significantly -- you could have picked up shares for less than a buck two summers ago -- the stock still trades at just 14 times the $1.25 per share that True Religion expects to earn this year.

iRobot (NASDAQ:IRBT) makes robots that want to eat your dirt. If that almost sounds sexy, stop and consider the vanilla-bean space of house-cleaning appliances. When was the last time the market got excited about vacuum cleaners and mops? No offense to the fine folks at Hoover, Electrolux, or the door-to-door Willy Lomans, but it wasn't until iRobot rolled out the Roomba that tidying up a home got exciting again. The company went public last year, and it recently upgraded its Roomba product lines and introduced its floor-scrubbing Scooba robotic mopper. iRobot is also a military darling, saving lives with tactical mobile robots for recon and roadside bomb retrieval. The company has been profitable for two years now, and last year saw sales climb 49% higher.

IMAX (NASDAQ:IMAX) is a movie star. With multiplex attendance declining for its third year in a row, IMAX has managed to grow its ticket sales and its new theater installations in that time. By giving folks a big-screen experience that no home theater could emulate, the same folks who have ditched the traditional movie houses have no problem paying a premium to see blockbuster releases on IMAX screens that can stretch eight stories tall. Earnings per share marched 53% higher this past quarter, and the company has received -- and is now considering -- several unsolicited buyout bids.

Nucor (NYSE:NUE) may be a steal in steel. Even though the Pittsburgh Steelers won the Super Bowl last month, most folks associate the stateside steel industry with depressing fare like Billy Joel odes about factories closing down in Allentown. Nucor stands out in a cutthroat industry by having better margins and a more attractive return on capital than its domestic peers. Stephen Simpson pointed out earlier this year that he liked Nucor's position in higher-value-added markets like structural steel and plate. He also likes that the company "invests in new technology, including, for instance, a casting technology to directly produce sheet steel in desired shapes and sizes."

Marking up the marked-down potential
Jeans? Home appliances? Movie theaters? Steel? It doesn't sound glamorous, but that's the point -- and the opportunity. Just as Southwest (NYSE:LUV) has been able to fly profitably above a runway strewn with bankrupt legacy carriers, there's no need to overbid in glamorous terrain. Not when you can find great prices and more elbow room in unloved specialties.

Nobody thought that the fragmented hardware sector would ever produce a winner until Home Depot (NYSE:HD) bled orange. It never dawned on the market that coffee sippers could be a mother lode until Starbucks (NASDAQ:SBUX) began percolating. Companies like Home Depot and Starbucks now feel so right, and their niches so obvious, but not long ago their believers were few.

That's why two of my four pretty stocks in ugly places have already been unearthed and recommended in recent issues of the Motley Fool Rule Breakers newsletter service. You can learn more about them and the many other monthly recommendations by going for a free trial subscription. Try it and see whether your portfolio is ready to embrace disruptive technologies as the opportunities that they truly are.

Don't follow the money. Follow the stink.

Longtime Fool contributor Rick Munarriz really does enjoy digging for opportunities where others aren't looking. He does not own shares in any of the companies mentioned in this story. iRobot and IMAX are Rule Breakers picks; Home Depot is aMotley Fool Inside Valueselection; and Starbucks got the nod fromMotley Fool Stock Advisor. The Fool has adisclosure policy. Rick is also part of theRule Breakersnewsletter research team, seeking out tomorrow's ultimate growth stocks a day early.