Confirms bias perhaps? I'm not really sure what you mean, if you go back two years you will see that posts have dramatically improved. Can you give some examples?

I'm afraid I can't say that I've noticed the trend you're talking about - the moderation team have removed literally thousands of comments in the last two weeks, so we're certainly trying to maintain a high standard! Perhaps you've just been unfortunate enough to keep taking a glance through threads before we've had a chance to deal with all of the offending comments (and on a large thread especially, rule-breaking comments just keep coming in).

In summary though, the best ways you can help to try and maintain the sub's high standards are:

• Report offending comments and threads (and if possible, use the 'Other' reason and quickly explain the reason, especially on a long post so we know immediately what the problem to look for is). This brings them into a queue of flagged posts where we can review them.
• If you encounter an unsourced post that you're dubious about the accuracy of, politely ask if that poster can share their sources and, if they refuse to or fail to in a reasonable amount of time (or if you're dubious about their sources), draw our attention to it with the report system. It is the right of every reader to ask for sources from a poster, including our flaired users.
• If you notice one user is being particularly problematic but seems to be going unnoticed, draw our attention via either modmail or by noting a bad post history in a report.
• Ask questions! We can define the parameters that limit the kind of questions people ask, but we can't force them to ask particular questions. If you think the number of interesting questions is slipping, try to think of some of your own, too!
• And if you have a friend or family member who happens to be an expert in a particular topic, please, relentlessly harass them into joining us and eventually applying for a flair! The more knowledge we have around, the more questions we can tackle and the higher the quality of discussion.

Could you give some examples?

Report questions and answers that you feel break the subreddit's rules:

https://www.reddit.com/r/AskHistorians/wiki/rules

I occasionally see shitty anecdotes when a gets enough upvotes to show up on https://www.reddit.com/r/all

The mods always remove them eventually though. You can't stop the post from showing up in /r/all, so there isn't really much else to be done.