There are a few variables there, like how long the deer sat around before it was caped. I wouldn't leave it in that state any longer than needed. Most guys think that it ok because the cape is cool, bacteria is still growing producing more of a threat on the cape slipping as time goes on.
Just took a whitetail in that was in a styrofoam cooler "on ice" for 5-6 days. To my surprise, the thing seems OK. Won't really know until after tanning. People think the capes will last forever just because they're on ice. On the other side of the coin, I've seen them spoil under similar conditions in 2 days!! You just don't know sometimes how it'll go. Typically, if it doesn't stink (like rot), and it's not slimy.....you're probably OK. If it's green (like the green you get from wearing a copper bracelet), it's too late.......normally.