Any decent amount of incompetence is likely to be viewed as a 'scam' by others. When you invert trust, in any portion of the business, you get what is generally viewed as 'privacy'. Bitcoin is essentially trusted privacy. Connect that notion of 'trusted privacy' to a business/controlling entity dealing with people's money, and you get fear. A 'scam' or fraud is defined as wrongful or criminal deception intended to result in financial or personal gain. Good reasons to fear.

A violation of trust when dealing with people's money is a perfect way to describe what happened at Mt. Gox, but it doesn't necessarily mean it was scam. That is only possible because Bitcoin.