refurbs come in brown boxes.
Not always. Beginning January I bought 2 Mac Pros from the Apple Refurb store.
One came in a brand new Mac Pro carton;
the other in a brand new PowerMac G5 carton.
Didn't notice it until packing them away.
Both cartons I could swear had never even been opened although to get the Mac Pro into the G5 carton I guess they must have.
Both had a label stuck on:

This is in the UK though. So I guess YMMV.