Unfortunately, not always. Here's a quote from the Snopes site...

it's all too easy for hoaxsters to fool reporters with demonstrations staged for their benefit (as notorious prankster Joey Skaggs has demonstrated time and again). Reporting the sensational draws a far large audience than debunking it does, so rarely do reporters engage in the necessary legwork to separate lurid reality from manufactured hoax. (The media all too often operate under the naive assumption that a hoaxster, having gone to a great deal of trouble to create, stage, and perpetrate a hoax, will simply come clean and announce the whole thing is just a joke the first time someone questions him about it. Therefore, if a hoaxster insists his outlandish venture is legitimate, it must be real.)