Here's the final segment on what to keep a wary eye out for during your travels. May you all have safe and scam-free journeys, wherever they may take you!
Driver or hotel claiming you damaged their property
I sat in the back of a taxi last fall in Morocco that had a large tear all the way down the middle of the opposite seat. I had my luggage over the seat for the whole ride, and when I paid the driver and got out, all of a sudden he started yelling that I had "ruined his seat" by destroying it with my bag wheels. He started swearing and demanding money, and people at the train station stared. A policeman came up and took my side, I think without even knowing what my psycho cabbie scammer was upset about, and the taxi driver quickly got out of there, so I got lucky (the policeman had dealt with this taxi driver before.)
Lesson learned? When taking a ride or accepting services from unscrupulous-looking individuals, avoid contact with all signs of physical damage as much as you can, because you can be blamed for them. Of course, shoddy hotels are also known for claiming that unsuspecting patrons have damaged the room. In general, when staying for several days at a place, you should clean up any cigarette butts, broken glass, or anything else potentially damaging before the maid comes in, or the hotel can get ideas about charging you for old burn marks, tile scratches, etc. Also, remember to report any existing damage to the room as soon as possible after you check in, or you could be blamed for it.
The tap water is "unsafe to drink"
Hotels in foreign countries (especially in Eastern Europe) will post "helpful" warning signs around your bathroom and/or kitchenette warning you that the tap water is not potable, and that drinking water must be purchased from the front desk (or worse, from the minibar). In many of these countries, water is perfectly safe to consume, but the hotel wants to sell you bottled water. In some cases, they'll give you bottled water, implying that they're free, but then add it on as a hidden charge later; this happened to me in a hostel in Australia a few years ago (and I actually believed that the tap water in Canberra was unsafe to drink... ).
To know whether or not the tap water is safe to drink somewhere, do your own research on the Internet (preferably your country's embassy guide), or ask a local. If you're unsure one way or the other, then buy bottled water -- at the nearest supermarket or mini-mart, not from the hotel.
Your tour guide or taxi driver will tell you that the hotel you've booked is closed, "no good," or too pricy, and that he knows somewhere nicer. While this might be true, the "nicer" place is giving him a commission for his referrals, and if you say yes and let yourself be taken somewhere you weren't planning, you make yourself vulnerable to more unexpected costs and detours. Furthermore, a stranger who is friends with your hotel owner now knows where you're staying.
What can you do? Stick with your planned hotel. An unfamiliar, flashy hotel that your scammer has just pulled you up to is always going to look more glamorous than your reserved hotel did when you saw the tiny pictures online; don't fall for it, and trust your original arrangements. If it's a "reputable" tour guide who's telling you to change all your plans at the last minute, you might consider ditching them altogether.
Help with buying the metro ticket
Do you love being self-sufficient by buying your own metro ticket in Paris, Rome, or other large cities -- but get tired of locals huffing and sighing behind you as you stumble around on the screen to choose the right train or fare? Local opportunists will gladly appear out of nowhere to help you purchase your ticket -- and demand a "little something" for their help. You should be very careful since at this point you probably still have your wallet out and you've just stepped away from the machine and no longer have the attention of the people in line who might actually intervene if your "helper" very discreetly mugs you.
In general, be leery of non-service person who goes out of their way to help you without asking you if you need them. If you're "stuck" as to how to purchase a ticket, remember that the person waiting behind you has an obvious interest in you getting what you want and moving on. Try asking them rather than waiting for someone to approach you in your moment of ineptitude.
"I've just been robbed!"
A clearly distressed person (often a woman, but can also be a man) posing as a fellow tourist will approach you and ask you if you know where the nearest police station is. They'll tell you they've just been mugged or robbed and don't have enough money to get back to their hotel, much less get back to their own city or country. When you suggest they talk to the police, they will tell you that the police "couldn't be found" or that there was a language barrier. The person will continue to be emotional (but not overly aggressive) until you break down and give them some money. Even if you don't give them much, these people can make a lot of money in one day playing the same dirty trick over and over.
Forgetting your change
A friendly ticket seller at a tourist site takes your cash, then takes a long time processing your ticket(s) all the while chatting up their colleagues, asking for your ID, and perhaps answering the phone on top of it. While you're busy looking around and waiting, your large bill has gone into the till and nothing has come out yet. A few minutes later the seller gives you a bright smile, some instructions, and says "bye!" so you'll leave. Once you step through the gate you remember about your change, but have no way of getting it -- or if you do, it's the ticket seller's word against yours.
To avoid being a victim of this scam, try vocalizing your transaction, such as saying "I'm getting 30 back in change, right?" as you're handing over your money. Don't let your eyes and attention wander until after you've gotten your money. The scammer will notice you're on the ball and find a more distracted person to shortchange.