In my experience, East Asian language speakers can often make perfect L and R sounds. The problem is that they don't hear the difference. Think of the English words "pray" and "play". The only difference between these two words is a single phoneme in which the tongue touches either the hard palate or the upper front teeth. English speakers learn to hear this difference because it can change the meaning. Likewise, Spanish speakers hear a difference between "pero" and "perro" that English speakers might not. Of course, we (English speakers) tend to have similar systemic trouble with their languages. For example, it is difficult for English speakers to hear the difference between Japanese long and short vowels, and, to the Japanese ear, we mispronounce "i" and "ii" often interchanging their pronunciations.

Don't know about Japanese or Korean. As a native Chinese (Northern standard Chinese ie Mandarin) speaker, I've never heard, at least I've never had the impression that the Chinese students around me mispronounce 'Please' as 'Prease' or 'Sorry' as 'Solly', even beginners who speak with obvious Chinese accents, I think I've been able to tell this. Speaking of 'R', and given American accent, most northern Chinese know a phonetic term called 'rhotic accent' which even is not well known by English native speakers but as an important concept, is very helpful to handle the 'R'. A northern Chinese like Beijingese can pronounce 'R' perfectly with American accent after a bit of practice even easilier than a British. As for 'l', you mean the letter 'EL' or just like 'lee'? The same, in Chinese there's a similar pronunciation that is marked as 'l' too. I know the 'pin yin' which was invented by the old English guy is horribly misleading for Chinese students to pronounce English correctly, but you have to say, pin yin is rather terrific and scientific. This is an example which 'Chinglishly' relates to something like 'Lee', 'ly' (the suffix of most adverbs) but just with a falling tone, please click on the little loudspeaker and listen to it carefully: http://dict.baidu.com/s?wd=%C1%A6&tn=dict http://dict.baidu.com/s?wd=%C0%EE&tn=dict

There is an American "R". It is introduced in the special English training course. Unfortunately, it is not the subject of ESL. The Asian are not taught to pronounce the "R" correctly. Moreover, when someone who pronounced the "R" in the corret way will be criticized incorrect. Threfore, the Asian are shy away to pronounce it correctly. Here, how many ELS speakers who claim to be the speaker with an American accent will accept that the "tt" is pronounced in "d" sound. For example: peanut butter, pronounce peanut buddah. " If they study our languages they practice proper pronunciation" - Mr. domasla

I had heard that they don't have an L sound in their language(s) and the closest sound they can make (without training) is an R.

It comes down to understanding the unknown based on what one knows. And as Daniel explained, it goes both ways. We sound equally weird when attempting other languages. We native English speakers have added a couple of extra problems by not telling learners that our "L" is thicker and heavier than in Asian languages. And worst of all, we do not have a standard pronunciation for "R"! I researched this recently, and found three unrelated pronunciations in US English alone (one speech terapist actually described eight methods), one of which is only vaguely related to my Aussie R, and another which is again only vaguely related to the Asian R/L equivalent. No wonder we're all confused. ;)