Ko Chang --> Cambodia?

Little surprise ripoffallerter gets riped off so often if he can not distinguish the official regulated buses from the cowboys

Thanks for the information about the official buses. I didn't know either that Thailand had this dual system of transport. Unfortunately tourists can't be expected to know this and Thailand does anything but help tourists in this regard, allowing numerous "cowboys" to operate right in tourist central and information is very hard to get on what is official and what is not. Official transport will sometimes rip off foreigners too, such as the case in Ko Samui where the baht buses refuse to take foreigners at the prices written in Thai inside the bus. Other times the official bus is not an option or too difficult to get to, so people end up with unofficial, and at the mercy of scam artists. Most of the time you just pay more than thais do, but dropping people off in unknown places at the outskirt of a city - especially at night -, which did happen to me in Thailand not once, is outrageous. Even more outrageous is what happened to travlora, we should be sympathetic instead of blaming the victim in cases like this. It's not reasonable to expect people to be untrusting of local transport companies, this phenomenon is unique to Thailand and possibly Cambodia, I have not heard people being conned this way in any other country.

We don't allow generalizations based on nationality or ethnicity, so I've removed a few posts. I'm sure you can debate the fascinating topic of bus scams without bringing an entire nation of people into it.

An addition on the bus system: You can charter your own transport for a specific purpose like anywhere in the world. This is not a bus service that runs an official line every day. Many Thai tour groups do this and there is a debate in Thailand about the appalling safety standards of many of these private buses.
Some enterprising people apply the same system to foreign tourists offering seemingly cheap prices on such trips as from CM to BKK, Phuket - BKK or Vientiane to BKK, and so on. They do a lot to insinuate that this is "the" bus. What is in common with these services is that buses leave from a GH or travel agencies and not the official bus station. This is a big red flag. Another bad indicator is the price. Once it is lower than the government bus then something is wrong. The lower price comes from overworked drivers, low standards of the bus and maintenance. Overall bus travel is not too safe in Thailand but the private companies/lines still beat this.
Add to that the cross-border services. They leave the customer at the mercy of the company. Cross-border buses should only be booked with official companies AT the bus station AT and official sales booth.

Songteaws are a different story and organized differently. They do not issue receipts like city buses or overland buses. In other words they can get away with anything you consent to, be it by force or free will. Usually these are cooperatives who work hand in hand with local politicians and provide the latter with strong hands when needed. Pattaya is a classic example. The same applies to motorbike taxis which try to dominate an entire part of town and serve as enforcers for what Thais call 'black forces.'

Night routes. Official Thai buses run overnite services timed to reach the final destination early in the morning, usually between 5 and 8 AM, some very long distance buses take a bit longer (i.e. Mai Sai etc.). You can book travel on these to places along the route. However, other than the day services the buses do not always pull into an empty bus station, very often they still do. In such cases they leave the traveler at an intersection on the main highway where motorbikes wait for customers. This is an established and known practice and no scam. The negotiations on price between the motorbike driver and tourists will certainly reflect the situation. So better ask at the ticket booth where the drop off will take place.
Some locations, Chumphoon comes to mind have a far removed bus station where buses come through with little transport to the center. This is a problem and no scam on the part of the buses. Chumphoon based companies offer departures and arrivals from the city center at their own terminal. Again, all is clearly marked and not a GH or tour agency office.
I should add that bus booking and arrangements in Cambodia resemble these private bus company agents in Thailand. Thus, confusion may arise. In SHV GH sell the 'real' bus tickets at a small mark up, usually 1 USD, for the buses.
We did not mention VANS. There are official van stops often at the official bus station sometimes at major traffic cross roads like Victory Monument in BKK. These lines are regulated, numbers, uniformed, official receipts given, prices fixed. Again, one needs to be clear about the drop offs and thus ask. Needless to add that travel agent are also in on that market and sell van tickets for supposedly existing buses and these vans are often old and driven by questionable drivers. No need to add the stops at overpriced restaurants, disappearing luggage, and other tricks to make more money.

In sum, some disappointments with official public transport results from a lack of information on the part of the tourist. Some is caused by the location of the official bus station which increasingly is found far from the city centers. Nevertheless, the buses are by far the best deal when it comes to bus or van travel.

Again, as stated before I did not blame travlora. On the contrary the input is important and will save some readers trouble and money. The OP highlighted the general issue of these private bus arrangements aside from the problems connected with this routing.

#21, in all the years we've been going to Koh Samui and take the red pickups have yet to see price lists inside. We hop on and give the driver what we reckon is a fair price. Ask his much and you'll get ripped off. Did notice last year there are more taxis and fewer of the red trucks. At taxi " depots" they do have price lists.

This is becoming boring. Apparently these scammers are not to blame, and they scam because they are poor, it happens in the West, or it is the victim's fault.
Or we are supposed to tell the difference from the regulated buses and the cowboys.
Regardless of the fact that the regulated buses also scam the foreigners.
Take a basic fact of bus traveling in Cambodia. They all charge the foreigner more for a bus ticket than a Cambodian.
And it sometimes happens in Thailand.
Does Greyhound buses in the USA do that?
Here is another scam the buses do on Thailand and Cambodia. the tourist buys a ticket, and the bus does not arrive.
Why, because they have not enough passengers to make money. They never admit it, and they expect the tourist to take a bus later.
It happened to a friend of mine who was going on the visa run to the border. He had to leave three hours later.

The info supplied applies to the Thai system as this was part of the OP's inquiry and also his later report.

I doubt that the claim "And it sometimes happens in Thailand" is true. In more than 15 years I had not one single incident that would lead me to believe this claim for a minute. I always do get my receipt; I always see the published price; buses run on schedule and not the number of customers. The authorities also welcome complaints. In case of a problem, keep you ticket. I never felt the need for such steps.

Buses might be delayed because of an accident, road congestion, and similar reasons. Companies like the Transport Company, Chang and many others do not sell tickets for non existent buses. Buses run on a schedule and they do so for years and years in a row.
It is dubious, to say the least, to make such unsubstantiated claims especially when it comes from a member who just has demonstrated his lack of geographical orientation and ignorance of bus connections on this thread. Such false infos lead to waste of time and money. Beware.

I m looking forward to read rippoff's report on his Koh Chang - Rayong - Aran bus trip adventure. It will be highly educational.

As for the scammers: The scammers working out of travel agencies are usually well-off when compared to day workers along the road. Thus, even that rant is nonsensical.