USD - KHR

Does $000 mean USD and 000$ mean KHR; seems they are use either way in classified section.

I'm pretty sure that both mean USD - most likely some people aren't aware of/don't care about the convention of placing the currency symbol before the numerals. The currency symbol for KHR is ‎៛.

Bear in mind that it's roughly 4,000 KHR to 1 USD, so if the quoted figure looks absurdly large it's probably KHR (and vice versa). You can use your own judgement.