Don't worry, just spray.
I bought the Caroline Vachetta against my better judgement because i thought I knew I would get it dirty. I put three heavy coats of Apple Spray.
So far, I've gotten ink on it (my hand was stamped, and the ink ran) and I got raspberry sauce on it. Both wiped right off with a Magic eraser ( I think water would a have taken them off too) and today I got caught in the pouring rain. It dried with out a mark. I throw it on everywhere and it's been a trooper.
I think the ink that got on it would be like a color transfer.
It's coming through with flying style. It's gotten a darker, not much that much though. I have no idea how it takes to darken, but it's going in that direction. I've has it about a month and it's my favorite bag right now.
But I've been shocked at how durable it is now. I was so anxious about spraying it, but I read you can spray it, so I figured I'd try.