Vent: GFCI kept tripping and the cause was nowhere near the outlet.
Put in a new GFCI outlet and it kept tripping right away. Found a wet wire splice in the crawl space that was feeding it. Took me hours to track that down.
Ugh, seriously, how far can water travel? I had a tripping outlet in my kitchen once and the actual problem was a tiny roof leak two floors up. The water ran down inside the wall and pooled near a junction box like twenty feet away.