Talulah said:
Sankaku has ~33M post IDs (I can't verify how many posts actually exist as status:any or status:active don't return counts), and ~15M of those are tagged tagme which means they may as well not exist as you'll never be able to search for them. IIRC a lot of the stuff not under tagme is just bot uploaded from pixiv with only translated tags as well.
Even worse at lot of the stuff not under tagme are CG/doujin pages bot uploaded from e-hentai with converted tag this mean that those image are poorly tagged. (for example if 3 images of a 500 images CG set contain an otoko no ko their bot will upload 500 images with the otoko no ko tag)
Sankaku is a cesspool and I finally stopped browsing it when they started bot uploading doujin/CG to the point of making their booru unusable.
The main problem with Gelbooru is the fact you need to solve a recaptcha each time you need to edit tags. That system discourage people from mass fixing images tags because the more you solve them the harder they get. One day I noticed that someone mass uploaded a lot of Digimon art from western artist without bothering to tag those artists (Gelbooru admin/mods should bonk that person). I tried to fix it but thoses recaptcha ended up driving me insane.