A number of cases I looked into featured the (in)famous Thai Katooeys (full op) or lady-boys. Before you laugh at the clients concerned, try the test on the INVESTIGATION ASIA face-book page.

Spotting a ‘Lady-boy’ or Katooey is often down to gut instinct and a case of the old if "she looks too good to be true" – she/he probably is ! A tall leggy brunette in stilettos, dressed to kill and waltzing along for all to admire is often a Ladyboy. They tend to have an exhibitionist nature so they love to have people look at them.

If there's some doubt and you are a fully heterosexual guy who is really only interested in the real and original thing, then here are a few general pointers:

1. SHOULDERS : Men's are usually square and noticeably wider than the rest of the body

2. FEET : A Ladyboy will want to wear sexy shoes – be sure to take a look at the size!!

3. ADAMS APPLE : but that is now being rearranged by the surgeons

4. VOICE ; The biggest giveaway, so listen carefully to your host. Katooey’s are very adept at disguising the voice, but it is one small giveaway – a bit gruff?

5. THE WALK : There's often an exaggerated swing of the hips to compensate for the fact that their hips aren't as wide as they should be and that skirt will usually finish just below the waist.

These are the usual aspects to look at ; without of course going for a closer inspection !
There are two less known differences between males and females, but these are not so easy to spot. Men have a straight wrist, whereas a female’s is slightly angled. More evident may be the elbow joint. A males arm (held out as if throwing a straight right ! ) is exactly that –straight.
A women’s arm however will bend back slightly past the 180 degree mark at the elbow.

As time goes by, the advancements in cosmetic surgery have improved markedly and it's very difficult to spot the boys from the girls and the Ladyboy – or the true Katoey, the one who has gone the whole way and been to the surgeon for a restructure not only to breasts but lower down.
Thailand is home to some of the world’s best trans-gender surgeons, many based in Phuket.
Their expertise doesn't come cheap but there are people who will pay enormous sums to get what they want, which may well be to be the most glamourous looking female possible.
Another fact about the Kingdom is that is has a very high percentage of females compared with males, and that leads to a high number of people who are sort of 'in between' – the third sex.
Take a close look at any department store cosmetics counter and you won’t often be absolutely sure if the person behind the counter is male or female.