Another way to tell if you're being had, I believe only white truffle actually contains dithiapentane or the flavor it mimics. So, if you're eating black truffles and it has that strong, distinctive "truffle oil" gas-garlic flavor, it's definitely added flavoring. The real thing is quite mild but definitely noticeable, especially the white variety. I'm one of those people that can't stand the fake flavoring. Luckily I'm currently living in an Italian truffle region and can get the real thing. As the article suggests, the best way to use real truffle is with a mild dish that can carry but not overwhelm the flavor, e.g. tajarin al tartufo (which I think was actually one of the images in the article).