There are several things that piss me off about Thailand. Sex tourists trying to talk down the price of bar fines. Cheap bastards carrying their drinks from bar to bar. And newbies who think it's cool to wai.
The wai is a minefield. It ain't a handshake, it ain't a high five, it ain't a way of saying hello.
Even a handshake is complex. You wouldn't shake hands with the CEO of your company. Or the waitress who serves you. Would you shake hands with your dentist? Your plumber? Trying to explain to a Thai when and when not to shake hands is a struggle. Well, the wai is a hundred times more complex. So in an attempt to stop more newbies embarrassing themselves, here are the rules about the wai:
Rule Number 1. Never wai anyone. The wai is a way of two Thais establishing where they stand in relation to each other. Who wais who and how serious the wai is depends on their relative ages, status, wealth, and family relationship. As a Westerner, you don't slot into the Thai hierarchy, so the wai doesn't apply. There are two views as to why this is so. The Western view would be that we are so far above them in terms of status, that there is no need to wai anyone. The Thai view would be that we are so inferior that a wai is unnecessary. Either way, Rule Number 1 applies. Any attempt at using a wai will result in you showing your ignorance.
The Thai who is lower in status initiates the wai. And the wai of the lower status Thai is more formal than the Thai of higher status. This is why it is so ridiculous when a farang wais a serving girl, a bargirl or a pimp. You are effectively saying that you are inferior to them (though in the case of most sex tourists, that's probably true).
A very serious, heavy duty, wai would mean the fingertips coming up to eyebrow level. A farang would only ever use such a wai if he met a very heavy duty Thai, and frankly very few farangs are ever going to get within a hundred yards of someone like that.
A serious wai would be the fingertips at mouth and nose level. It's the wai that a child would give a parent, or a pupil to a teacher. That's what you will tend to get from waitresses and hookers, but they don't mean that they are according you higher status, any more than a United Airlines air hostess means it when she tells you to 'have a nice day'.
A regular wai would be the fingertips at chin level. That's the wai a higher ranking Thai would give to a subordinate in reply to a serious wai.
A perfunctory wai would be with the fingertips at chest level. It's not a wai to be initiated, it's a half-hearted reply to someone who is giving you a wai.
The regular wai and the half-hearted wai are the only two wais that should ever be attempted by a farang, and only as a response, never as an initiation. But remember, Rule Number 1 always applies.
Rule Number 2. Sometimes it's okay to wai a monk. All Thais wai monks, no matter what their status. The average sex tourist is not going to come into contact with a monk, but some might go up country with their temporary girlfriend and be taken along to the local wat. If you are introduced to one of the local monks, then it is okay to wai. But the monk won't expect you to. He knows the score. You won't be the first sex tourist to be taken to his wat, and you won't be the last. Follow your girlfriend's lead. If she wais, then you can. Tips of the fingers no higher than your chin. To be honest though, the monk is going to be more interested in how much money you give to the wat than whether or not you wai him. Rule Number 1 still applies.
Rule Number 3. It is sometimes okay to wai old people. Not just any old people, though. Just because someone is older than you doesn't mean that they are automatically accorded more status. But if your temporary girlfriend introduces you to her father and mother, then it is okay to wai them. Fingertips no higher than the chin. They should return the wai. If they don't (and that happened to me once, a long time ago) then you should be in no doubt as to what they think about you. You can wai them when you first meet them, and when you say goodbye. You have to know that you are in fact older than your girlfriend's parents, of course. In the case of most sex tourists, they are usually the same age or even older than the girl's parents. If they are in fact younger than you, then they should be initiating the wai. They won't, of course, because they will think themselves superior to you, because they are Thai and you are farang. Rule Number 1 still applies.
Rule Number 4. It is sometimes okay to return a wai. As a Westerner, Thais will occasionally wai you. Sometimes as a greeting. Sometimes as a 'thank you'. Do not give them a wai in return. Simply smile and nod. Maybe say 'sawasdee krap' or 'chok dee.' (Be lucky). Remember, Rule Number 1 always applies.
You will often be given a wai by waitresses and bargirls. Just smile back. Hotel staff will wai you. Just smile. So who would you return a wai to? Remember, Rule Number 1 applies. But there are a few occasions when maybe, just maybe, it's okay to return a wai.
If your temporary girlfriend introduces you to younger members of her family, and if they are not in the sex industry, and if they seem sincere when they wai you, then it's a nice gesture to wai them back. Fingertips at chest level is okay. If your girlfriend has kids (a fair bet) and if she introduces them to you (unlikely, but possible) and if they wai you, then it's okay to wai them back, for no other reason than the fact that you are teaching them good manners. Other than that, Rule Number 1 applies.
Rule Number 5. It is sometimes okay to wai in return for a service rendered. This is far less complex than a greeting wai. Thais will wai you when you do something for them, and this usually involves giving them money. Just smile in return. You never return a wai given for a service rendered. And Rule Number 1 applies.
Should you wai someone if they do something for you? The simple answer is no. Rule 1 applies. Generally, a Thai is only going to be doing something for you if you are paying them. The money is your way of saying thank you, the wai is superfluous. If a Thai does do you a great favour and isn't being recompensed financially, then you might consider a wai.
Oh yeah, don't bother giving a wai to a policeman. He will either take a bribe from you, or take you to jail. A wai will make no difference to the outcome. Rule Number 1 applies.
Okay, them's the rules. But you don't need them all. Just remember Rule 1. Never wai anyone. That way you won't look like a Newbie.