We use bunch of warm(!) water and a big soft sponge. Just put lots of warm water and those sticky dirt is removed by the sponge. Be careful though as not every mare likes it. My qh really enjoys (she starts sucking my neck with lips when we do it - very, very ticklish), my paint hates it (she actually kicks out).
I do it without any gloves. I've heard horror stories here about smelt, and (yes, I know it's funny
) I took hands to my nose as well as my mom did out of curiosity while cleaning there and there was NO SMELT at all.