As mentioned yesterday, the risk in correcting others is that you get exposed to correction yourself. So it turns out to be -- sort of -- with my comments about the L and R sounds in Japanese. Major point: it remains correct to say, as I did, that Japanese speakers do not "lallate" -- use Ls in place of Rs, and vice versa. Minor refinement! It's not quite right to say, as I also did, that the Japanese phonetic system "has no L sound." Its writing system has only Rs instead of Ls (when represented in the western alphabet), but the sound is more complicated. Representative messages:

"I think it is more accurate to say that Japanese has a single sound that is somewhere in between English 'l' and 'r'.  The Japanese 'r' is certainly not standard US retroflex 'r'.  Say the name "Richard" and feel where your tongue goes (it's back towards the roof of your mouth).  Now say "baseboru" with your best shot at a Japanese accent - you'll find that your tongue is further forward in your mouth and just taps the ridge of your gums.  Now say "Lilly" - your tongue will be even further forward.  The 'r' in 'baseboru' is somewhere in between  "Lilly" and "Richard". " [JF note: this corresponds to my experience in coping with Japanese.]

And, from someone raised in America whose husband was raised in Japan:

"Yeah - they use "R" when they write those syllables in Roman alphabet.  I've learned though that my pronunciation is somewhat less comical to the listener if I pronounce it closer to the English "l" sound.  As best I can make out, the tongue position makes it something of a cross between our "r", "l", and "d".

I believe there is research showing that a newborn is able to "hear" most any of the sounds you can make, but by the time you are 3 or 5 (or somewhere in there) your brain has specialized for the sounds you normally hear.  My husband simply cannot hear the difference between the spoken "l" and "r", because there just aren't those distinct sounds in spoken Japanese.

Also, from someone raised in Taiwan:

"I agreed that in Japanese, they spelled both English "L" and "R" with "R". But it will be incorrect to say that they have trouble to pronounce "L". It is actually the other way around, that is, they have trouble pronouncing "R". They simply don't curve their tongues.

"I contribute this mix-up to the mistake they made when they Romanized their language. The ra / ri / ru / re / ro sounds you mentioned actually should be pronounced closer to la / li / lu / le / lo in Japanese. This is the same problem as people in Taiwan called 台北 Taipei instead of Taibei, with the later closer to the Chinese pronunciation and the same with calling 高雄 Kaohsiung instead of Gaohsiung. I am from Taiwan and I still don't understand why they did this....
"PS. By the way, I did have a Korean professor who actually "reverses" his L and R every single time."