IDK, it really depends on what the exact problem is, I guess. The last time I really ran into that problem was in Les Mis fandom, where nobody was tagging their #$^@#$ modern AUs. Sometimes you could get around it by filtering out other things associated with the specific AU (either on Google or AO3), or filtering in tags that wouldn't appear on modern AUs (i.e., "post-barricade), but mostly we started tagging non-modern-AUs with canon-setting tags and made collections and recs lists.
If it's something like ignoring-canon-after-a-certain-point you can try filtering in things like episode tags after the divergence point? Or if it's an AU that suddenly got popular you can try date ranges, or things like that.
no subject
IDK, it really depends on what the exact problem is, I guess. The last time I really ran into that problem was in Les Mis fandom, where nobody was tagging their #$^@#$ modern AUs. Sometimes you could get around it by filtering out other things associated with the specific AU (either on Google or AO3), or filtering in tags that wouldn't appear on modern AUs (i.e., "post-barricade), but mostly we started tagging non-modern-AUs with canon-setting tags and made collections and recs lists.
If it's something like ignoring-canon-after-a-certain-point you can try filtering in things like episode tags after the divergence point? Or if it's an AU that suddenly got popular you can try date ranges, or things like that.
But mostly, cry.