gia

You all know that fan. He or she spouts out the dozen or so Japanese phrases that he or she knows regardless of whether those around him or her would understand them, wears a kimono or gi at inappropriate times, eats everything with chopsticks no matter what, and tries to sit seiza style whenever the opportunity arises (and usually has to move after a few minutes).
  
I was reading this blog post earlier about a woman of Indian descent (that would be Asian Indian, not Native American) and how frustrating it is to deal with people who appropriate aspects of her culture (from yoga to Indian medicine and cuisine) and exoticize it, combined with dealing with those who would hold that culture against her. There are also a lot of comments in the post, a handful of which talk specifically about the manga/anime phenomenon. Which got me wondering, as one commenter asked: at what point do you cross the line from cultural appreciation to cultural appropriation?
 
I suspect that on some level, anyone with an interest in (for example) Japanese culture will always seem like a poser or an outsider to many native Japanese, myself included. But that doesn't mean I'm not familiar with people who take such interest to a whole different level, and how irritating they can be just to me in general, much less to a "real" Japanese person. 
 
What do you think? Where would you draw the line? How do you make sure that you're appreciating another culture and not trying to appropriate it for your own? Or do you think, as some of the commentors on that post did, that some level of appropriation is natural, particularly in the melting pot that is America?