One of my Thai friends taught me a word which can be used to describe a how a girl uses her feminininty as power over men. I understood this word could be used for men towards women (kind of like the thai equivalent of he/she has sex-appeal).

The Thai word is Sa-nee .. e.g. pooying thai mee sa-nee. I thought it was a useful word to know.

Later on when I used this word, another friend told me that this was a very upolite word and not to use it as it made me sound gay in addition to being rude.

So ... what's the truth?

Is this a case of miscommunication with the person who taught me (or maybe a practial joke) or is my second friend being too sensitive.

Another word I've got mixed signals on is Nian (meaning horny). I guess it is also very unpolite way to say this. True?

'Ngian', yes, very unpolite. According to standard rules, shouldn't be used with anyone except for your close male friends or out of the bedroom (even there, many "nice" Thai girls do not like it, so tread carefully). A more polite word for horny is khrai (falling tone, short vowel sound), meaning to be in great need of something, not necessarily sex. Since the subject itself is not the most polite of conversational matters, any words in this department need to be handled with a sense of when they are appropriate, this you will learn by listening to other Thais and watching their reactions.

As you may have noticed, foreigners speaking Thai are expected to be more polite than the Thais themselves - clearly a double standard, but that is the way it is.

As for sanee, there is nothing unpolite about the word itself, so your friend was either just leading you on or misunderstood what you were trying to say.

I was taught sa- nee as meaning charm.

I often hear the word in thai songs and it is also the title of a thai magazine so I do not think it can be impolite .

However I do not know if this is charm as in attractive personality or charm as in 'put a spell on someome ' . I suspect the latter.

เสน่ห์ (sa[LS]-neh[LL]) is a perfectly nice word that is used in many situations.

Although the word is most often translated as 'charm', to my mind it's slightly stronger in meaning than the English 'charm', more akin to 'allure'.

It can also be used for inanimate objects. I'm reading a book right now called เสน่ห์ร้านเก่า (sa[L]-neh[L] raan[H] kao[LS])--The Allure of Old Shops--about shophouse architecture in Thailand.

It's a lot better to say a woman has เสน่ห์ than to say she doesn't. ไม่มีเสน่ห์ (mai[FS]mii[M] sa[L]-neh[L]) leans toward insulting in fact.