The thing to remember is if there is enough leakage current to to trip the GFCI there is also enough leakage current to kill someone if the appliance loses it's EGC.
A gfci works like an amprobe- as long as the total flow = 0 when "probing" line and neutral together the gfci assumes safe functioning. capacitors act a little like a battery where they draw current without returning it the gfci reads current leaving and not returning and "detects" a fault.
I'm sure the capacitance value has a strong bearing on whether or how often the gfci is fooled into thinking the appliance has faulted.
A gfci isn't an intelligent object it's very good for protecting people from shock conditions but cant distinguish shock condition from normal function.
I havent heard of the hosedown approach like washing a boatdeck but it wouldn't surprise me
thanks for the input guys, I'm really enjoying this site