John,
Yes seems bonkers that there's such a deterioration etc. My lower bonnet side venting is designed to feed air in as opposed to venting air out - ie the slots are flat open forward on the outside with the risen louvers to the inside. I think this exacerbates the situation feeding weather in etc. You might find yours are the reverse. You may also find your plugs are fine and this may be a part of that. Happy exploring anyway. The Platinum plugs are much cheaper than they were some years back so I guess there's some good news!
Cheers
