I can't imagine that very fine droplets of water would affect the actual engine, they would go straight through the relatively large fuel jets. I suppose a large proportion of suspended water must by definition cause a reduction in power output but I'm sure this would be an extreme case and would be visible to the naked eye.
However, suspended water MAY affect the contents gauge readings where capacitance type sensors are used, a gauge over-read would occur due to the water content.
I also understand that the presence of suspended water gives more of a storage problem because bacterial growths can occur in it.