Indeed...I play COD4 competitively on PC even today on a daily basis & I can very well tell that the ground & other textures in this game are avg. to bad & the competitive mod on which we play [Pro mod] strips the game off from most of its graphical capabilities like Shadows,Particles & what not.
But in the end I notice it for like the first 5 minutes the day I played it for the first time & then those thoughts NEVER came back into my mind. I am pretty sure that its the same case with the console version's sub HD reso as well. Atleast the console players are not the guys who play the game with no shadows,particles & special effects