A violent sneeze heaved a mass of gunk over the MacBook Air's keyboard. Very messy. Fortunately the Uppercase Premium keyboard cover caught the lot, it was just a matter of removing the cover, washing & drying it. $25 well spent. Good insurance.
I used to have a Moshi cover which was 0.2 mm thick, but I lost that one somewhere, no idea where. This new one is even thinner.