Is it becoming more and more difficult?
My long held belief that Thai food was generally very healthy has diminished fast. The diet of rice is generally healthy- the accoutrements of creamy sauces and fried meats are not.
Problems with pronuncing R and L
Perfect pronunciation in my experience is pretty much the last aspect of a second language to properly fall into place. However there are good reasons why Thai and Korean students should be shown very clearly exactly what they have to do to come up with an unambiguous ‘r’ and ‘l’, and the sort of problems that are going to stand in their way.