The issue with brake fluid is not the colour but the fact that it is hydroscopic. This means that it attracts water just like the wee packets you get with electrical and optical equipment.
Once the fluid has water in it the fluid can then be compressed. Water is softer than brake fluid. If this happens you need to change it. Boiling the fluid also increases the chance of water vapour getting into the fluid as the water has the opportunity to replace the air introduced during the boiling.
If you want the best fluid you get synthetic (silicon) see
http://www.automec.co.uk/frame_set.html for some info
The reccomendation to change your brake fluid according to specified service intervals is because it is not easy to ascertain the level of water molocules in the fluid hence change regularly to be on the safe side.
From reading the posts thus far i would reccomend that you check to see if you have
A contaminated pads (grease or oil on them)
B a siezed pot in one or more calipers. this would mean that the pads are only pushing against one face of the disk. Are the disks clean on both faces and over the whole area?
Does the brake pedal bottom out?
If it does then it may be excessive wear in the pads a leak or fluid.
If it doesnt then it points to a lack of effectiveness at the coal face ie wheel end.
Will any wheels lock up??
) Seems a bit odd seeing as it's still a bit wet. 
) and on the last one, keep your foot hard on the pedal for 2 mins whilst stationary. I found that helped with mine when they felt a bit soft.