Transcript for Never Have a Bad Cup of Coffee With These Barista Secrets
Here's a question for you tonight. Can you smell it in your favorite coffee shop? The pumpkin spice? Well, tonight here, the baristas baring it all on what happens behind the counter. Here's nick watt. Reporter: The holidays are coming. I can tell, just by visiting the coffee shop -- chestnut praline, cinnamon hazelnut, peppermint mocha, winter warmers. But hold off on the caramel brulee eggnog gingerbread frappucino -- I made that one up -- until you've heard our insiders, our baristas coming clean, tell us how to get the most out of your holiday fix. Baristas are basically drug dealers. Reporter: Former barista Hayley and current barista max say you and I are the addicts. So, when the, you know, junkie comes to get his fix, he's not gonna be super polite. He's just really focused on getting what he's there for. Reporter: So, max and Hayley created this video. It's a parody of "I dreamed a dream" from the musical "Les miserables." ? Wait your turn and stay in line ? ? we all have a place to be ? ? now I shall drink the drink ? Reporter: They call themselves "Les miserabaristas." It was all my pent up sadness and frustration. And I took it to a creative outlet. There's one instance in which this lady told me, "You don't know what you are doing?" And so, I took the caramel drizzle and I wrote the letters "Fu" on top. Reporter: So, if you've been rude, check your pumpkin spice latte for hidden messages. And then, there's this guy -- I had a customer threaten to stab me one time. Reporter: Let's call him "Bill." He still works at Starbucks and writes a blog called "Your barista hates you." He insists on full disguise because he fears he'll get fired for spilling the beans. Our number one tool in the arsenal is definitely the decaf button. Reporter: They'll decaf when you ordered caff. Just out and out rudeness is a quick way to get a decaf shot. Reporter: They will steal your buzz away from you. I've given decaf to people who wanted the extra caffeine. Absolutely. Reporter: The problem for a barista though is that you're out in the open. You're not back in the kitchen where you can spit in the soup. If someone's being particularly rude, you can add little extra charges. Like, normally if you say, I want a latte with caramel, vanilla and chocolate. Reporter: The barista could charge you just once for a wee dash of each. Or, if you're unpleasant, charge you three times. That's like a dollar difference, at least. Reporter: So, you're being nice. You're not gonna get decaffed. But how do get the most caffeine possible, maximum buzz for your buck? Apparently not with this. The frappuccinos are mostly ice, very little coffee. Our profit margin on frappuccinos is huge. Reporter: And when it comes to lattes at Starbucks -- just order the medium. The large does not have more caffeine, just more steamed milk. Whatever your choice may be, we were told to go for a light roast. Dark roast has less caffeine. Dark roast, less caffeine. Reporter: Executive coffee chef Jeremy gursey -- yes, that's now a thing -- knows his roasts. According to Jeremy, iced coffee can be the most potent. This is my pride and joy. This is a Kyoto, eight-hour, cold filter, drip. Reporter: That is delicious. Oh, my goodness, there's texture, it's kind of -- oh, yeah. Like a fine bourbon. Reporter: Clearly, I'm now an expert. But the real experts, the baristas we talked to say that you, the customer, really have no idea what you're drinking. There are the select few who are truly coffee aficionados, but the vast majority of my customers actually don't really know anything. This is nice coffee. Reporter: Remember that '80s, from before we got all fancy pants about a cup of Joe? We're secretly replacing the fine coffee usually served here with rich, dark, sparkling Folger's crystals. Reporter: We did something similar at local favorite philz in Santa Monica. We lined up a cup of supermarket standard -- 5 cents a cup. A premium java from a well-known coffee chain -- two or three bucks. And a third -- the most expensive coffee on Earth. It's a blind tasting. Are you like a coffee type guy? I drink coffee every day. Reporter: Patrick guessed this is the most expensive. It's the cheapest. Patrick, we have a total failure! I hope I don't get this wrong. Reporter: I hope you do. Take your time, swill away, do whatever you need to do. Ashley guessed the coffee chain coffee was the most expensive. It's far from it. So, maybe we really don't know what we're drinking. And what is that mystery most expensive coffee on Earth? This, $75 a cup. This one? Is that that coffee where the bean comes out the monkey butt? Reporter: Nate, clearly a connoisseur, was almost right. Indonesian civet cats eat coffee berries, they ferment inside and out poops the beans. Nate, by the way, nailed the taste test but still thinks maybe coffee chain coffee isn't quite worth it. So, do I think I'm getting fleeced and used? Of course. But will I continue to do it? Of course. Reporter: The barista guild of America told us, "Since the invention of coffee drinking by the ethiopians, making coffee for another person has been a deeply caring and personal act." This is a real organization, by the way. "We use service skills to help us navigate challenging customer interactions." As for Starbucks, one of the most admired companies in the world, it told us it is appalled by bill the barista's claims of decaffing rude customers. "The behavior described would not be tolerated and is not reflective of the character of our 300,000 partners around the world." So, how do you get on your barista's good side? Know what you want before you get to the register. Reporter: Good tip. And speaking of tips -- Tipping also helps. Oh, yes. If you put in that dollar, we will remember you. Saying, how are you, back is really nice. Reporter: And by the way, our bearded confessor tells us that if you order a coffee on a holiday and tell a barista "Too bad you have to work today," you most definitely will get decaffed. So don't be a dope. You might even get a treat even sweeter than three pumps of peppermint. People I liked I would reward, give them a little extra whipped cream or draw a little smiley face on their cup.
This transcript has been automatically generated and may not be 100% accurate.