Voici les points communs des hoax:

• it suggests tragic consequences for not performing some action.
• it promises money or gift certificates for performing some action.
• it offers instructions or attachments claiming to protect you from a virus that is undetected by anti-virus software.
• it claims it’s not a hoax.
• there are multiple spelling or grammatical errors, or the logic is contradictory.
• there is a statement urging you to forward the message.
• it has already been forwarded multiple times (evident from the trail of email headers in the body of the message)

Tiré de US_CERT: http://www.us-cert.gov/cas/tips/ST04-009.html