I had this happen on our return trip in July (MCO to DEN). I noticed the suitcases, one in particular, felt kind of wet as I was loading them into our car. When we got home, I was going to unpack just the essentials and save the rest for the following day. Well, I started to unpack and realized everything was soaking wet! I couldn't leave it. Stuff was already ruined (a DVD player met its demise on that flight as did a hair dryer, my kids books, a pillow, and all of our paper souvenirs, including the banshee boxes we unfolded and out flat into a suitcase). I immediately called and notified Southwest. They had me photograph everything but have never done anything about it. Makes me angry, but what else can I do? It's been 6 weeks at least.
I still have no idea what happened. It wasn't raining in Orlando or Denver. People bringing home all of their unfinished water? Seems unlikely but could possible. My kids said everything was wet like the suitcases fell into a swimming pool, and they're right!
I am giving serious consideration to investing in hard-sided luggage. I don't like what I'm reading here, that other people have arrived to this kind of mess?! What a disaster! The only good thing I can say about this is at least it happened to us coming home. It would be a nightmare to arrive in WDW to soaking wet luggage. Next trip I am lining the suitcases with large trash bags and packing everything important (clothing, DVD player, etc) in ziplock bags.