Alrighty friends! It takes some specificity, but you can do this. Let me show you how!
So I started with going to the Sherlock (TV) section of Ao3. On the right we find this lovely section! ((I know I’m going over things you already probably know, but I figure this post may go to new Ao3 users, so bear with me.))
Underneath this, I chose sort by Kudos, because that’s a quick way to find most popular fics, for the sake of this demonstration.
With those filters on, we end up with this being our first two results:
As you can see, we have Nature and Nurture by earlgreytea68, and The Internet Is Not Just For Porn by cyerus. So what if I am utterly sick of seeing earlgreytea68 on my list? Let’s pretend I’ve read all their fics, or that I just don’t like her, or whatever. I want this author out. I go to this section on the right:
In “Search within results” I type earlgreytea68 into the bar, with a minus sign in front. This gives me the following page, upon hitting the sort and filter button:
There goes earlgreytea68! But now I’ve decided that Crack is just not my thing, I’m sick of that, too, for heaven’s sake, I want something reasonable in my gay slash fanfiction about detectives that solve crimes about glowing dogs and irish megalomaniacs. Heaven forbid this get ridiculous.
Well, then I add this to my search:
Which gets rid of everything with that tag. My results are now:
Performance in a Leading Role is now my first result!
You can do this as many times as you want; the biggest problem I have is trying to filter out multi-worded tags. For example, “Secret Relationship” is hard to filter. Better to go with authors you dislike or with words like “DubCon”.
I hope this helps! Also remember that googling site:archiveofourown.org and then adding search terms will mean google searches Ao3 for you, and sometimes that works far better.