Transcript for Dirty Little Secrets from the Dry Cleaners
Once again, "True confessions." Here now, Rebecca Jarvis Reporter: You hand the dry cleaners your most precious, your most irreplacable garments and what do you get back? You shrunk it! Reporter: Not always what you thought. Annoyance at the dry cleaner is so common. It shows up in TV and movies all the time. I don't see my Yankee Jersey. It's must be gone, I'm sorry. What? Dry cleaners sometimes don't have the best reputation. Reporter: Jerry Pozniak runs "Jeeves," sort of the rolls Royce of New York City dry cleaning. But tonight, he's letting us in on "Dirty little secrets" of the industry. It makes you angry. It does make me angry. Reporter: Secret number one -- scummy solvent. Let's face it, dry cleaning is a mystery for most of us. The key to the whole process, says Pozniak, is this. The solvent. It's supposed to look like this. Clear as a mountain stream. But the stream can turn to a swamp according to Pozniak. It's kind of like taking a bath and you have bath water and five other people took a bath before you and then you got into that water, would you feel clean when you came out? Reporter: Pozniak says some dry cleaners cut corners and increase profits by neglecting to filter the solvent enough. Eventually this gunk is left behind. So that's what my clothes would be laundered in? With dirty solvent. Exactly. This is the bottom residue of dirty solvent. Reporter: The industry insists this residue won't touch your clothes but even so -- if your dry cleaner isn't taking care of his solvent your white dinner jacket could end up one of the 50 shades of gray. Secret number two -- no work for the jerk. Pozniak says most customers are great but if you act like a jerk, complaining about how something came out, he's heard of places that will only pretend to reclean the clothes. At bad dry cleaners, yes, I've seen it. Reporter: And secret number three, your stains tell all, yes, some dry cleaners are keeping tabs on you. And the embarrassing stains you bring in. Lipstick on a collar, or whatever on a dress. No one knows more than the dry cleaner. Reporter: It's cringe-worthy. On TV. I didn't do that. Reporter: Or in real life. Ever gossip about people what they've brought in? When I was working with my dad, we had a client we had a nickname for, he was Mr. Condom. Because every time we had a pair of clothes from him we usually found a condom. It was so disgusting. Reporter: Lydia Noone knows every secret and every secretion of the cleaning biz. There are the customers that always have gross stains on their clothes, it makes you wonder "What are they doing?" Reporter: Lydia works at "20/20" today handling other kinds of dirty laundry. But while she was in school, she made extra cash behind the counter at her local dry cleaner. So, we decide she's perfect to do our dirty work. A kind of test of dry cleaners. Which dry cleaners? Lydia begins by loading this dryer with the names of over 1,000 located in New York. And the winner is -- Reporter: After a quick spin, she selects ten places to check out. And what will be their challenge? That requires a visit to the stain master. We have ten identical pairs of khaki slacks and ten identical white shirts. Reporter: Meet Alan spinvogel of the national cleaners association. Using yellow mustard, red wine and blue nail Polish. Like a degas of dry cleaning, he paints equal stains on each garment. They are difficult stains, and if they can remove these stains, they can probably remove any stain. Reporter: Impressive work but we wanted to test the cleaners honesty as well as their competence, so Lydia adds something extra. A ten-dollar bill in each pants pocket, Pozniak isn't confident I've heard of places it's "Finders keepers." Reporter: What will be removed? The mustard spot? The wine spot? The nail Polish spot? Or the ten spot?? We are about to find out. Lydia, along with intern Haley peck, loads up a car with those befouled shirts and khakis and heads off. The ten cleaners are in Brooklyn, queens and Manhattan. From the high-priced spots in the "Silk stocking district" to a low-rent outfit near housing projects. Get nail Polish out? I don't know. Reporter: Lid Ya and Haley record the drop-offs. This will be ready by Monday. Reporter: It will be a few days before we can see what comes out in the wash. You legal I don't know. Reporter: So in the meantime, we dig more dirt with Debra kravet. She runs apthorp cleaners, a top flight spot we aren't testing. She has a few more dry cleaning secrets you need to know starting the moment you stain something. What do you recommend people do, is club soda the answer? Club soda is definitely not the answer. If it was we'd all fill up our cleaning machines with club soda! Reporter: Secret number four, no club soda! She says club soda does nothing except possibly make the stain worse. Instead, gently dab the spot with a white napkin, or do nothing at all. True or false "Dry clean only" means you have to dry clean it? No. Reporter: That's right. Secret number five, labels lie! For certain fabrics, like cashmere sweaters, handwashing is just fine. As long as you don't put it in the dryer. And secret number six, the gender gap. Janet palmer was hotter than a steam iron when she discovered the dry cleaner charged her more than her husband to clean shirts. Exact same shirt? Yes. Different size? Yes. Two dollars more. Yes. Reporter: Outraged, palmer decided to call 50 dry cleaners in New York City. And while we can't say its true everywhere, she found women on average paid 73% more. 73% more for what? I have no idea. Reporter: Our experts tell us its not sexist, it's economics. Women's shirts cant fit on a pressing machine and have to be hand ironed, more labor equals more expense. Maybe so, but Janet palmer was so put off she's boycotted dry cleaning for years. But not our Lydia. Our shirts fit on the presser. So no extra charge, but are they clean? And what about the 10 bucks hidden in the pants? How many cleaners gave the cash back to us? Sad to report, but get this, out of ten cleaners just one. One. The other nine charged us "The sticky fingers tax." What's up with that? Now, the moment of truth with those stains? Lydia goes to vartest, an independent lab where they perform scientific stain analysis. Overall, it's a mixed bag. The nail Polish was the toughest, only three out of ten got that out, while nearly seven out of ten were able to clean the wine stain. As for the mustard on the pants, only six out of ten succeeded. But our biggest surprise, the cheaper spots did better than the fancier places with the supposed expertise. And you don't know what goes on behind closed doors. Reporter: Kravet and Pozniak agree. Our test proves customers need to sample dry cleaners themselves. You just can't pick a dry cleaner by the one that's closest in your neighborhood. Reporter: And stick with whoever wins!
This transcript has been automatically generated and may not be 100% accurate.