not sure why you resurrected a >2 month old thread to comment but since there's 2 sides to every coin, I immediately got a keyboard protector when i purchased my 11" mba for the sole reason to protect against spills, and exactly 2 months later, I spilled a quarter cup of milk over my mba where it ended up just running along the bezel and seeping into the grills, immediately shutting it off and costing me $755 to repair it (thank god amex protection covered it). This just got me to realize that it just takes a specific type of spill to render a keyboard cover useless.
look at me, i'm resurrecting an almost 2 year old thread. why? because people search the forums for these kinds of topics and this particular thread happens to be the top returned search on google for "best skin macbook air"
how many threads on the front page are questions that have been asked 8 million times already? without even looking the good money is on at least half.
regarding your post itself, a "quarter cup of milk" is still a substantial amount of liquid!
that's one and a half of these:
and milk no less, a better conductor than water. not to mention "grosser"
that skin may not have saved your computer but there is no way you would have been better off without it. 60 mL of liquid right onto your computer is almost certainly going to be pretty deadly with or without a skin.
sorry that happened, glad you got it fixed - 'm still putting skins on my machines, hopefully you are too!