So I understand what you mean with the "Smut" prefix, but I'm looking at this from a fanart perspective, and finding it rather tricky. What qualifies as "smut" in a standalone image, especially when it's appended to a freeform that isn't directly related to sexual stimulation? (For example: to draw "Smut - Shibari Under Clothing," would I need to draw someone getting fucked, clothed, while shibari is peeping out? Or would a drawing of a character blushing as another, leering/smirking character unbuttons their shirt to reveal ropes be smutty enough?)

I suppose one could avoid offering those prompts as an artist; it's just kind of disappointing, especially when quite a few of those freeforms lend themselves very well to visuals (and don't have a non-prefixed counterpart).