I think being aware of the issue & trusting other people's descriptions of their experiences is an important step. Recognizing that you don't see DMs, follower-only replies, or replies from servers your server has already blocked. That (depending on your server/client software) you might not see lots of other replies which may not be hateful but still annoying in their redundancy. That dismissing complaints & demanding proof or explanations on its own makes people feel unwelcome.
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