I took one pair of flats on a weekend wedding trip (I like packing minimalist).
It was an outdoor wedding in the country. And it rained all. weekend. long.
When we finally made it back to our hotel post-wedding, I had to decide between disgusting muddy and wet, or just sopping wet (after cleaning them in the hotel tub). I went for the latter. I even tried drying them with the hotel hair dryer the next morning, but after an hour they were still soaked.
The next morning, I squished into Target, found the cheapest pair of flip flops I could find, walked barefoot to the counter, and wore the flip flops for the remainder of the day and the drive home (we were visiting friends in a hospital on the way home, so I had to have shoes). My flats are currently air-drying on my back porch, so we'll see how long that process takes (it's already been two days of air drying and they're still damp!)
So, long story short, purchase made. Back on the wagon.