2003 Protege, only 50,000 miles... really. We bought it new, she never drives it.
Very rainy outside = random misfire problems. ( we don't have a garage)
put some warm water in a new spray bottle, gave a LIGHT spritz, and got this :

( click on the picture to play the video)



NOTE: NEVER hose down a motor with a garden hose ! You can bend/break/warp alot of very expensive parts !

You can see the spark jumping at the bottom of the boot at the coil.
Off to the parts store for set-o-wires !

edit: oops, I should have titled this "cause of", not "cure for"...

 

Hmmm.... nice! I would run some die-electric grease around the inside of that boot.

I had a similar issue with a Honda Civic I owned years ago. I couldn't kill that car if I tried, but let it get humid or rain (I didn't have a garage either) and she wouldn't start until I took the distributor cap off, wiped it out and sprayed it down with silicone spray lube. Then no more problem, until the next time.
In the end, it turned out that I had gotten a faulty dist cap the last time I tuned her up. Had a hairline crack in it I could never find. I replaced the cap and no more trouble. That car was great!! I wish they (Honda, or anybody else) still built 'em that way.