@GuusV every so often I'll get a solid bit of fluid come through but generally it's just a mixture of the both
After replacing the master cylinder we determined that the throw out bearing has also gone bad as it been on its way out the last couple months and the slave cylinders piston was pushing to far out as it had to much resitatance and was causing the bleeding to failYou should have a good solid sequence of only fluid coming out for about 3 or 4 times. (so, if you get a bit of air a few times, don't stop. Keep going until you get only fluid 3 or 4 times in a row)
The process should be: (really requires 2 people)
1) apply pressure to the clutch pedal (push it to the floor).
2) open bleed screw on slave and let fluid/air escape, make sure that the pedal continues to have pressure on it, press it to the floor and keep in there
3) close bleed screw
4) "pump the pedal" (4 or 5 times). This may have to be done by hand if the pedal does not return to the up position on its own (move the pedal by holding on the the foot-pad with your hand)