Those remind me of when you take a bunch of old crayons and melt them together. @_@
I can post a tutorial for my pants if you guys want me to. For these pants I would *think* you could dunk a pair of jeans in some red dye for a shorter time than it recommends OR maybe even take a pair of red jeans and dip them in that Rit color remover stuff for just a bit to fade them out.
The rest of the colors don't really look like splatters to me and you probably wouldn't want to use that much fabric paint (what ive used on my pants) or they'd get really stiff. Maybe more experimentation with different fabric dyes again?
Loving all the fun pants that have been coming out lately!
ETA: thanks for linking me Girl X!