Hearsay can be and in many cases is 100% factual.
No it's not. Thats why it's called hearsay. If it was 100% factual it would be called fact. Something can only be called fact if, at the time of it's disclosure or declaration factual evidence can be provided.
Something appearing on an internet site, or in a newspaper as a rumour, which later may turn out to be true, is still a rumour until proven otherwise.
You can't listen to or read some rumour and say "Well, i'd better believe this as it MAY turn out to be true down the line".