Scams Alert! (as seen on Wikitravel)
Most local are decent people just trying to make an honest living but a few shady characters try every trick to take advantage of travellers good will. Be alert to deceptive dealers, but don't let suspicion ruin your trip.
1. Convenience stores have been known to give incorrect change and pocket the rest. Check your change before you walk out of the store and point out any short changing. Most likely they will admit to their "mistake" and give you the right change.
2. Street vendors and beggars in competition for generous travellers' handouts have developed cunning, if underhanded, techniques to get your attention (and money). The "beggar army" of young children will come up to you in the crowd and grab your hands, leading you to a store where they will then try and have you buy food/baby milk/water for them. Baby milk (infant formula) seems to be a popular one. It might sound like a more humanitarian way to help than simply giving them money, but once you leave the store the goods you bought for them are sold back to the store owners or to other locals and the cash goes to an adult. Young women with babies cradled in a krama perform a similar trick.
3. Donation-collectors for orphanages may approach you in the street claiming to be volunteer workers, showing you convincing photos of themselves in the orphanage and a clip board listing the generous donations made by foreign travellers. Though these young adults may be well groomed and speak excellent English it's possible that your donation will go directly into their pockets. A donation (either of money, or your time) to a recognised Charity might be a better way to help.
4. Baby-milk scams may be encountered in the centre of town, outside supermarkets. A very poor looking woman will beg for some milk powder, pointing to her baby. If one cracks and buys the milk, she later returns it to the shop, and the money is split half-half.
5. Border-Crossings: POIPET: There are a few bus operators running Siem Reap - Poipet - Siem Reap. And they are most likely drop you off at their BASE/COMPOUND. So it's difficult for any travel to negoiate a better way for tuk tuk ride to town center. Please be AWARE of organized-scam when you purchase your bus tickets from anywhere in Thailand. They're not always reliable and honest to what they tell you.. And sometimes people in Cambodia get to buy tourists like commodities. It's very dodgy and messy.
As of 1 April 2011 travellers departing Cambodia by air do not pay the International departure tax at the airport, the US$25 fee is included in the ticket price The $12 Domestic departure tax is still paid at the airport. Try to pay in cash as the credit card facilities are unreliable.
Siem Reap International Airport  (IATA: REP, ICAO: VDSR) is the second largest airport in Cambodia. Its modern architecture is based on the traditional Khymer style. Its facilities are limited. There are separate terminals for international and domestic flights.
The airport is served by:
The airport is around 7 km from the town centre. Prepaid taxis cost US$7, see the prepaid booth just outside the terminal. Prepaid tuktuk rides for slightly less are also available. Thrill seeking solo travellers without much baggage can save a few dollars by opting for back of a motodop for US$2. Most hotels offer a free airport pick-up if you've booked in advance.
Major companies include Phnom Penh Sorya Transport, Capitol Tours, Sokha Komartep, Mekong Limousine Express, Giant Ibis Luxury bus.
Try to book at least the day before travel. Travel agents and guesthouses will do this for a US$1-2 fee. Buses tend to leave in the morning or early afternoon. There are also night buses on some routes.
Many buses terminate at an out of town bus station to the east of Siem Reap, from where travellers will need to take a tuk-tuk into town. This should cost no more than US$2, or maybe $3 if you're not keen to drive a hard bargain. Anything more will have your driver thinking you are a weak-willed idiot, rather than the generous, naive optimist you perhaps consider yourself to be.
If arriving from the west, Bus Station of Siem Reap is NOT really functioning: Different bus has their own little depot and where they drop their passengers. They seldom drop people at the common bus station. If you cannot give your hotel/guesthouse correct name of bus and time of departure, you have little choice but to face the touts especialy when you come from the WEST/ Poipet border. Big TIIME organized-scam around there..