I've spent the last hour or so scouring the internet to find the answer to this question, but to no avail so I thought I'd put it to you all.
Ghost touch armor says:
This armor or shield seems almost translucent. Both its enhancement bonus and its armor bonus count against the attacks of corporeal and incorporeal creatures. It can be picked up, moved, and worn by corporeal and incorporeal creatures alike. Incorporeal creatures gain the armor's or shield's enhancement bonus against both corporeal and incorporeal attacks, and they can still pass freely through solid objects.
My problem with this is that in the last sentence it says incorporeal creatures gain the armor's or shield's ENHANCEMENT BONUS against both corporeal and incorporeal attacks. Does this mean that if an incorporeal creature...let's say a ghost...was to wear Ghost Touch armor that didn't have an enhancement bonus, then it wouldn't get any bonus to AC from the armor?
For example, I have built a ghost ranger who is wearing Ghost Touch Breastplate. The breastplate has an armor bonus of +6, but no enhancement bonus from being magical. Does that mean the ghost doesn't get the +6 armor bonus?