I literally washed an A1200 motherboard with water. This was after having gotten sugar-laden milk on it.
I literally used regular tap water (soft) until all the crap was shifted. I then used distilled water to remove any minerals that might be left behind by the first rinse. Finally I dried sensitive areas with IPA (isopropyl alcohol) and then let the thing dry for several days in a warm, dry cupboard.
Was absolutely fine afterwards.
This is exactly what I've done in the few cases where an air compressor wasn't enough. Water (possibly with baking soda and a toothbrush if it's really nasty), rinse with distilled, and IPA. I buy the IPA from the local electronics joint, since the regular variety sold here leaves a residue. I'm also careful not to soak any stickers present on the board.
