I believe everyone is correct. Shooting with a fouled barrel is inherently more accurate due to the fact that you zero with a fouled barrel.

Leaving it dirty all the time is not great for the barrel either.

Solution? I clean my rifles after every hunt and range day. Just before the hunt, I foul the barrel either at the range the day before, or in the field if I can shoot far from where I'll be hunting. It does not take many rounds to foul a barrel sufficiently