...though what you said in the PM kind of worried me. Are the player sprites in places where I won't see any spoilers? :S
It is
every image extracted from the game, so story spoilers are imminent.
To severely decrease the chance of getting spoilered, turn off thumbnails in the folder and all subfolders.
WARNING: /System has
extreme amounts of spoilers. It includes, of all things, the ending. Do not touch unless you seriously want to.
/Battle is obviously clean.
/Character is a mix up. /display_01 is the only clean folder in there. /event has miscellaneous sprites and the sprites in the /Character folder themselves have sprites of the spoiler bosses, but if you don't look past Byakuren's sprites (012_白蓮 in /event, 012_20.png in /Character), you won't get spoiled, but that's still a bit risky. /object_01, /object_02, and /symbol have stage spoilers.
/Chipset is tiles for all the stages and therefore has stage spoilers.
/Icon is clean on story spoilers, but it will spoil you on the total amount of skills in the game by showing you what icons exist for which skills and which do not, so if you want to discover what kind of skills are in the game without flipping through a folder, do not look in that folder. It also contains the ABP icons and the item icons, but they're not as interesting.
/Monster, obviously, has story spoilers.
/Panorama is the same as /Chipset, displaying the battle backgrounds and such. Stage spoilers.
/Stand contains the final boss Last Word cut ins, so I assume that you would use the archive in Pooshlmer to find the non-spoiler folder of that.
/Weapon has no story spoilers, but it will spoil you on all the weapons (including God Hand). As with the /Icon folder, look through it only if you don't want to discover how all the weapons look by yourself.