Whenever you play against someone, just make sure all the ground rules are set up first. If it is a personal concern, bring it up and agree on it. Items/options not mentioned can be construed as fair game. Take nothing for granted. Once agreed upon, I would expect my opponent to uphold their end of the bargain.
I've never personally changed unit names with the intent on confusing/misleading anyone. If one is careful, renamed units doesn't really work. It's a chore to do anyhow. I went through that phase in my games against the AI to visibly group my units by name. Obviously, it's not going to confuse the AI. The last thing I want to do anymore is rename 100+ units in the hopes that I
might confuse my opponent. With proper tactics, they can be defeated anyhow.
I'm not sure name changing really falls in the realm of "fog of war". Not much fog if a SABOT round whizzes by your tank. Seems to be more along the lines of "deception". It might be splitting hairs, but I view "fog of war" as just natural consequence of a confusing battle where as changing the unit name is an intentional attempt to deceive your opponent. Before long, we will be including Quaker guns and Patton's inflatable army in the game
