And what do they do to make you spend more? Tonight, true confessions. And we start tonight, with spy cams to see what happens when you leave your car in the wrong hands. Here's nick watt tonight.... See More
And what do they do to make you spend more? Tonight, true confessions. And we start tonight, with spy cams to see what happens when you leave your car in the wrong hands. Here's nick watt tonight. Behind the wheel. Reporter: We are in los Angeles, where the car is king, where valets are everywhere, where the horror stories are legendary. To find out if the tales are true, we've hired the ultimate bait car. A $70,000 tesla. And it has an optional accessory, our hidden cameras. We've done some research on the internet to find some places that have complaints about their valet parking. And we're taking our car to those places right now. And before long, oh dear, we're capturing scenes like this -- yup, right there, three valets crammed into our exotic, electric sports car, making it their own, checking it out, playing the radio, opening everything that opens and shuts. They even take the tesla for a quick spin around the parking lot. But are scenes like this the exception? Or the rule? Who knows who you're giving the keys to, really? It's more like valet parking roulette. Reporter: Ed Ryder is on board, a real life valet, dishing the dirt. What's your boss going to say when he sees you on TV? There's going to be some heat, yeah. I might not have a job after this. We'll see. Reporter: For now, at least, ed works at an upscale hotel in Philadelphia. He says scenes like this, seen on youtube, valets gone wild at this St. Louis hotel. He's says they're real. He says you should be afraid, be very afraid. Rough driving is not unusual. I'm talking about full throttle acceleration, heavy braking, hard cornering -- that kind of thing does go on. Reporter: And damage does happen. Ed took these photos of bruised and scraped cars carelessly treated. This valet narrowly avoids disaster after he forgets to apply the emergency brake. Another valet wasn't as quick on his feet. And this Hyundai sonata somehow ended up not on, but in, the dock down in ft. Myers beach, Florida. All that's left, the spare tire. So what happens in a damage situation? It's really up to the customer to find the damage themselves. We're not going to point it out to them. Reporter: So if it's a scratch, the valet code is -- You keep your mouth shut and hope the customer doesn't notice. Once you pull off the lot, that's it. It's -- they can forget about any compensation pretty much. Reporter: So ed has just started his own business -- real valet control, selling these valet cards where you enter mileage, pre-existing damage, making the valet realize you mean business, that you will check for damage before you drive away. But ed's not entirely innocent. I brought the car up front. Pulled it up to the curb and somehow I grinded the right front wheel onto the curb. Reporter: So the customer came out, didn't see it, drove off, end of story. Yup. Reporter: You still feel a bit bad about it, don't you? I felt terrible. But the supervisor said, "Don't feel bad. She didn't tip. So this was, like, preemptive karma." Reporter: Okay, back to our high-performance bait car. Would our tesla be in for rough treatment? Now, if I was a valet parker, I just could not resist doing this. And neither could this valet at an upscale restaurant, testing the tesla's power. Tearing off so fast we couldn't keep up with him in our undercover chase van. Did we lose him? I have had a couple valets when they give me my car back say to me, "Wow, that car's really fast." That's a compliment, right? Not a good sign. I would say. Reporter: Now after paying eight bucks for parking, you'd expect our beloved tesla to be kept in a safe and secure lot. But check out this valet. He ends up parking our $70,000 baby in this back alley -- a very dodgy-looking back alley, at that. Another valet simply left it on the street. But what if you've left your car with a valet overnight? We've all heard the urban myth that valets take cars home at night. Well, watch this. It's a myth no more. ? thanks to prince, who doesn't want to drive away in a little red corvette? Well, in 2012, my ABC colleague Jeff deal of WFTV in Orlando dropped one of these beauties, rigged with gps, at a valet lot for cruise passengers. A few hours later, his phone beeped. The 'vette was on the move. And the station's chopper was in pursuit. That is the owner of the valet lot joyriding on dirt roads, zooming down the highway to dinner at Applebee's, visiting ace hardware, loading in some lumber. He drove more than 60 miles in two days and, yup, parked overnight at his own house. Jeff deal swooped in. You recognize those people in the car? We're not driving anybody's car. So -- You're going to say you weren't driving that car? Be honest with us. Sir, you're completely wrong. Reporter: While ed says most valets are just hard-working, honest guys, tales abound of sticky-fingered valets making off with your valuables. Stanley Arnoux, the saints linebacker, allegedly had his super bowl ring stolen by a valet at a posh Miami beach resort. So, what happened with our tesla test? The good news, most places were absolutely fine, nothing taken. We left some cash in the car. Those inquisitive valets we saw earlier? They find and gleefully brandish that cash. These two valets at L.A.X. Thumbed through the billfold as well. For whatever reason, these guys looked, but they didn't take. But this valet who works at a luxury Hollywood hotel had no such scruples. He has no idea he is being filmed. There, he's found the money. He's counting it out, and, oh my goodness, he takes a $20 bill and slips it into his pocket. So I paid a visit to the manager of the hotel's valet stand. We left our car here. And unfortunately, $20 was stolen by one of your valets. And we have it on film. Do you know him? Yes. Reporter: People give you their cars and I don't think they expect this to happen. Are you surprised? Yes, I am. Reporter: Has this kind of thing happened before? No, it hasn't. Reporter: I mean, do you tend to have a lot of problems with the valets? No, not at all. Reporter: What advice would you give somebody who's giving in their car? Should people just take their valuables out of the car? Pretty much they should take their valuables. Reporter: Just so that it's not a temptation. Exactly. Reporter: So how else can you give yourself the best chance that your valet won't indulge in any monkey business? Simple. Ed gets paid j.83 an hour. The quickest way to a valet's heart is be quick and generous with the baksheesh. Start out by putting a tip on the dash. Reporter: Before -- Yes, when you arrive. Reporter: Preemptive tipping? Yes. What that does is it helps to influence the level of care your car's about to receive. Reporter: When you look at somebody, can you tell if they're going to be a good tipper or not? No, you can't tell. Reporter: Really? Unless they have a foreign accent. Reporter: And then they're bad. Thank you. Of course, we didn't learn about this whole preemptive tipping concept until after our hidden camera shoot. And maybe that's why this happened. We love your accent, nick. And the national parking association tells us their members are committed the safety and taking care. When we come back, contractors.
This transcript has been automatically generated and may not be 100% accurate.