I must apologise for this sobering post but I felt a fair number of people were making dangerous assumptions and taking unnecessary risks when having sex.
First, let me point out that nowhere in South East Asia is it compulsory for ladyboys to be checked for STDs (sexually transmitted diseases). Therefore the onus is on the customer to look out for his own health. Yes, there are some responsible ladyboys who go for check-ups but it's impossible to know who's doing it and who isn't and also when they last went for one!
Here are just some links that provide some details =
What do Symptoms of Sexually Transmitted Diseases Look Like? (very graphic) - http://www.thebody.com/content/art2307.html
Reducing the Risk of Getting HIV From Sexual Activities - http://www.thebody.com/content/prev/art2503.html
Brief Condom Fact Sheet - http://www.thebody.com/content/prev/art51354.html
Basically, using latex condoms is the most effective way of preventing STDs. You may not get the most pleasure but not using one is like playing Russian Roulette.
So guys and ladyboys, sorry for spoiling your fun but this is essential stuff and can't be ignored. Trust me, I've seen an AIDS victim and most of us wouldn't want your worst enemy to suffer that way.