Bitcoin is perfectly fungible. Anyone who claims otherwise is confusing economic concepts.
we already had this discussion.
maybe bitcoin is technically fungible (because any coin can always be send an mixed) but practically you have problems when using coins which where stolen (eg bitstamp hack) or why do you think new minted coins are sold with a premium?
My point exactly. You can mix them, but in the end someone is going to end up with coins from a theft (assuming they were stolen in some form or fashion).