Not to stir the pot, but I would differentiate putting larger wheels/tires, body part add-ons, interior/stereo changes, suspension or engine mods, etc. (all of which I see as perfectly legitimate personalizing or customizing a car to one's own tastes and pleasure) from sticking on a fake badge which implies the car is something that it is not [you don't see AMG themselves putting their badge on anything other than cars they have produced -- and certainly not on cars that only have AMG wheels or body kits that you can buy from anyone]. What do you think Hans Werner Aufrecht's reaction would be?
Put another way, the badge is a form of communication -- what are you trying to say [or what do you want others to think]? Would you sew a Gucci label on a non-Gucci jacket (for instance, to advertise you are wearing Gucci shoes)? To me, it just says "poseur", but I guess everyone's free to strike whatever pose they want.