I do it so much, that I actually make drawings and notes on my fridge in the garage. The green seems to be the hardest to wipe, but the spray cleaner (or just alcohol or Windex) wipes it right off.
Go for it!
Keg #1: Bourbon/Oak Vanilla Porter
Keg #2: Cascadian Stout
Keg #3: BMC West
Bottled: Mjolnir Mead, Lazy Daze Hefe, The Bollocks ESB, Dark Matter stout.