Goron,
I too have had little success in removing this type of dye.
As it is sprayed on the skin it must be resistant to water otherwise any perspiration would cause runs
, so a solvent approach is the way to go.
Different polymers /dyes are soluble in different solvents.
I would try hydrocarbon ( white spirit),alcohol (isopropanol,eco spotter etc), acetone( nail varnish remover0.
Initially I would put onto white towell and gently rub to see if there is any dye transfer.
If there is none then probably best to save time and money by recommending they spray in a hard floor area
Cheers
Doug