There was that Paradise Vision clip a while back called "Bella Gets Her Feet Washed". It's 5 minutes long, f/f. Don't remember soapy water, though.
There's a fantastic video of Viviana in a bubble bath, again Paradise Vision, where she's tickled by Kamiano. I don't remember her soles actually getting bathed however.
There's also a really nice video, an older one, by Foot Cuties (aka Hang Ten? Same company?) called Lisa's Tickle And Tease where, again she's in a bubble bath, and has her feet scrubbed and cleaned. Don't remember if there's soap suds involved, but it's a hot clip from what I remember.
It's upperbody, but watching Kamiano clean the body paint off of Jade is one of the hottest clips I ever saw (yet another Paradise Vision clip).