A couple incidents:
I was out with my grandson at a scene of a small river with waterfalls and "tidepools" and such, we were sitting at the bed as I snapped photos. My grandson picked up my camera bag, and out tumbled my 70-300 IS lens, out and into a pool! I had to scramble down into the dang pool to fetch it!
Well, back at my place, I set my oven to a low/warm setting and put the lens in with the oven door part way open. and after a few hours I checked, it still showed moisture inside, so more heating. After about 2 days I checked it out, and voila, the lens worked, AF, IS and all!
Not so happy about the time I was out doing some street shooting. I had my 50mm f/1.4 in my bag, on my car seat. A friend went and pulled it out, and the lens fell out and hit the pavement. The 50 is a bit notorious for having an AF that can get pretty messed up, and that was the case -- I couldn't myself fix the thing and so I sold it to another photographer for dirt cheap!
One more thing, I had a fair amount of activity with my Canon 85mm f/1.2, an amazing and expensive lens, but the time came when I had to sell stuff to pay bills, including the 85. Well, someone came over to check things out and noted that there was a crack on/in the lens case, down by the base! Well, I hadn't dropped that lens, but I guess it had seen some rugged use, I checked it out and the crackage showed down the body and into the rim where the lens hooks up, so it was a mess.
I brought the lens into a shop, with some parts documentation, and a helpful tech took it in and repaired it and gave it back to me for $120, not bad at all, the lens sold in a heartbeat!