I believe, in the court of law, all evidence is required before making an accusation.
This can and should occur in fandom spaces dedicated to making call out posts and hate campaigns.
If your only source is word of mouth that shows no evidence or examples of the "crime" someone committed, then their argument and accusation is moot.
If you're calling someone a misogynist you need to provide evidence, in a world relying on social media presence and easily accessible history, that should be easy enough.
If you claim plagiarism, then you need to provide evidence of both the work that stolen something, and the work that was stolen from. Your word is not more valuable just because you claim they did something wrong.
Provide evidence or cease your accusations.
If someone is racist, show proof, timestamps, the context of the post and even more importantly, how old is the crime, and has the person since saying or doing the crime, ever acknowledged or apologised.
If you accuse someone of something you also need to be willing to hear their side of the story, especially if the evidence is minimal or taken out of context.
If you are not willing to hear the accused side of the story, then you are biased and likely hearing from inflated or twisted version of the story.
If an accused refuses to acknowledge or they deny their claims, then that is in fact their side of the story. If evidence is minimal with no proof of crime, and the accused has proof of not doing said crime. Then by that statement the likely evidence for said crime is fabricated or inflated to make the accused worse than who they are.
If you listen to only those who hate the accused, and never people who side with or are neutral of the accused, your opinions are biased.
You need to pull out receipts, you need timestamps and evidence of both acknowledgement of the crime and all affected parties.
It's why I do not trust most call out posts. Because half of them are little snippets of insignificant things without real evidence. If they are old examples (anything above a year is old enough) then you need to provide also evidence of more recent things or if the accused has acknowledged it.
I was informed a longer creator was racist. But then immediately after they rescinded their statement. Saying the accused's crimes were more than 3 years prior, with both an apology and acknowledgement from the accused.
Whilst it's not my place to claim complete forgiveness, the continuing of spreading this accusation does nothing more than holding back a person of growth, and refusing to listen to improvement.
A call out post is not just for the masses, but for the accused to better themselves as a human being. Bar from actual crimes regarding real children, animals and sexual assault.
Almost any action can be amended. If they've changed, then accusations cease if they continue then accountability must be had.
The most important thing however is, if the person shows willingness to change or wanting to change. Then further accusations will not help the accused, it only hinders progress and makes it harder for any real change.
You need to be willing to allow the accused to in fact change who they are as a person and grow from their mistakes. Bringing up past mistakes does not help.