Having lived in Thailand I can tell you that this problem is not particularly new. Sure, all of us who lived in Bangkok could spot and tactfully avoid the ladyboys pretty easily, but it was always amazingly easy to fool the novices, newcomers and those that didn't know what to look for. You'd be surprised how competently the gender reassignment surgery operations are done (and have been for awhile), and Thai trannies rarely look like linebackers in drag the way their Caucasian/Black counterparts do.
Thanks for the warning. Yes, I’ve seen some of them stateside.