My experience with gut shots have been a very stinky arrow and a gritty substance on the arrow. No green, just gritty stomach material.

My experience with lungs and heart is a very bloody arrow, pink and or red blood.

My experience with the " hollow spot" , if it exists, is an arrow with very little blood on it, almost like you described, wet to the touch, but not by blood. Do you think you hit high?