Facts CAN NOT be attacks. When you make such idiotic decisions, you really have to dim-witted to think that your opponent will not point such mistakes. Obama attacked her, Chaffe did, Web did, O Malley did in 1st debate.
None of those politicians promised to run positive campaigns. Bernie has.
Pointing out a fact would be saying "Hillary voted for the Iraq War."
Attacking is "When we talk about foreign policy, we need to recognize that it's important to consider the judgment of a leader. In 2003, I voted against the Iraq War. Hillary voted for it. That was a clear lapse in judgment, and I think it reveals fundamental flaws in her character."
or "I do not think it's controversial to point out that someone who took money from Wall Street can never change Wall Street. When you are a politician who is bought and paid for by Wall Street billionaires, it is impossible for you to bring about real change."
The fact that they're not heavy, blunt and loud like Trump doesn't mean they're not attacks. It just means they're very well-crafted attacks because they're calm and subtle and don't automatically repulse people. Bernie is a very skilled politician and has a crack team working for him.