I entered something in my blacklist, and when I search for a certain pic that's NOT covered by blacklist tags, it blacklists anyway. And when I delete the blacklist ALL the blacklist tags, the same posts are blacklisted.

GET OFF YOUR ASSES AND FIX THIS SHITTY ASS SITE MODS!!!!

xbooru.com/index.php?page=forum&s=view&id=29

Its because of the ranking of the pic. i.e. the "vote". If its negative, its not going to be shown, unless you set negative numbers to be shown in your blacklist section.