Hmm... usually it washes out for me. I think you just have to get in there with a damp cloth and try to scoop it out.
or you could do a 2nd rinse and when the washer has some water in it, try to scoop up the floaters (ew)
If it's a top loader, fill the tub with water and then skim of the top, like with a mesh strainer or a piece of screen. This is what my sister did in college when she moved into an apartment that boys had partied their last night away in -- meaning trashed the place and left, not before they puked in the washer. Gross.
You might want to pick this up while you're at it...