Sportsmanship and ethics are entirely different. Ethics is a measure of your belief system. A kid taught jack-lighting by his parent believes that to be ethical. When one is taught to hunt within the boundaries of what is legal, that too is ethical behavior. Now taken in a vacuum, which is more ethical than the other?
My perspective of people discussing ethics, is that they need to confine that conversation to their circle of experience and refrain from making pronouncements that may affect others when they have no right in the first place to call any legal hunting activity anything but legal, and ethical.
A sportsman behaves in a legal and ethical manner. A sportsman will take shots that he knows he can accomplish. A sportsman is not driven by the need to kill, but more by the need to challenge himself. A sportsman shares his self with others to further the "sport" of hunting. A sportsman will try to council those that he sees are less gifted or experienced that he. A sportsman will certainly not belittle or criticize hunters fresh into the ranks, nor will he criticize legal behavior. He might, when he sees a shot for example that he wouldn't take being taken want to find out more about why that individual took that shot. The answer's sometimes can be humbling.
If one doesn't like ground sluicing, in MY OPINION, the way to present that is IN MY OPINION, is to say something like, "while shooting birds on the ground is certainly legal and maybe an assured way to harvest dinner, I prefer to flush the birds or have the birds fly from under our dogs as I think it is more of a challenge for me and helps me develop my shooting skills more so than does shooting birds on the ground. You make your point.
Aloha...