Laos has nothing like the organized tourist-scam culture of bigger regional cities. Vientiane is calm, violent crime against visitors is rare, and most problems are small and avoidable. The list below is what actually recurs in traveler reports, and the simple habit that defuses each one.
Tuk-tuk and taxi overcharging
The most common one. Drivers quote tourists a multiple of the local fare. Agree the price before you get in, have your hotel write the destination in Lao, and ask staff what a fair fare is. Easier still: use LOCA or KOKKOK Move, where the fare is shown or fixed in the app before the ride, so there is nothing to negotiate. After 10pm, book through the app or your hotel rather than hailing on the street.
The "temple is closed" line
Near hotels and the Morning Market, a driver may tell you Wat Sisaket or Pha That Luang is closed for a Buddhist holiday and offer to take you somewhere else — usually a shop or restaurant that pays commission. The temples are almost always open. Go and see for yourself, or check with your hotel.
Torn and damaged banknotes
Badly torn or taped kip notes are hard to spend, and some money changers and vendors pass them to tourists. Look at each note before you leave the counter and hand back anything damaged. The same applies in reverse to your US dollars: bring clean, unmarked bills, because damaged dollars are refused everywhere.
Short-changing
At markets and small shops, wrong change and prices that shift after you have paid are the usual friction. Count your change on the spot, confirm the price before handing over money, and type the agreed number into your phone calculator so both sides see the same figure. Kip has many zeros, so double-check whether a quote is per item, per kilo, or per person.
Motorbike rental disputes
Most rental shops are honest, but reports of inflated damage charges, and occasionally of a bike "stolen" from where the renter parked it, do recur. Photograph the bike from every angle before you ride, note existing scratches on the contract, use your own lock, do not leave your passport as a deposit if you can avoid it, and choose a shop other travelers recommend.
Alms-giving pressure
At the dawn alms round, touts sell sticky rice to tourists, urge them to join the line, keep refilling the basket, and then demand payment. If you want to take part, buy rice at the market beforehand and offer it properly; otherwise watch quietly from across the street. See the temple etiquette guide.
Drugs in Vang Vieng
Some bars and cafés in Vang Vieng still offer "happy" menus. Drugs are illegal in Laos, penalties are severe, and travelers have reported set-ups where a purchase is followed by a police stop and a demand for a very large cash fine. Decline, every time.
Gem "investments" and too-friendly strangers
A well-dressed stranger strikes up a conversation and steers you to a family shop selling gems that will "triple in value" back home. Laos produces almost no gem-grade stones; any investment pitched to a tourist is a con. The same goes for unsolicited offers of cheap tours or special deals from someone who approached you.
Everyday safety
Bag-snatching from passing motorbikes happens occasionally: carry your bag on the side away from the road and keep your phone in a pocket until you need it. Use ATMs inside bank branches or malls at night. Exchange money only at banks or licensed changers, and count it before leaving. Lock valuables in the hotel safe. If something does go wrong, the Tourist Police in Vientiane handle visitor complaints, and your hotel can help you reach them.