I've heard of modelers that use only distilled water for wet-sanding. Also, there was an earlier mention of using paper towels; as an aside, Bounty paper towels are not made using recycled materials...just food for thought.
Back to the topic at hand, a soft 1/2 " paintbrush will also help with those "Stubborn stains". A bit of distilled water, a dab of dish soap, and you're good to go.