Clutch not building pressure
 

I recently bought a 2005 Civic DX coupe from a friend of mine. I knew going into it that the car needed some TLC. When I popped the hood I immediately noticed that the clutch reservoir was missing the cap and that there was a layer of white silt sitting on top of the fluid and that the fluid itself was as dark as coffee. I went ahead and bled the system but after the bleed the clutch was not building pressure and the pedal was all the way down on the floor. After some research, I replaced BOTH master and slave cylinders and again bled the line. Still no pressure, so I replaced the line with the same result. Mechanically there is nothing wrong with the clutch as my friend was able to drive the car before I bled out the fouled up fluid. I am curious to see what y'all think could be going on. Could there still be air pockets in the line that I just gotta keep trying to bleed out? I've had a helper help me bleed the line and even used our shop's vacuum bleeder. I would appreciate any advice y'all have. -- Akodo