Join Date: Jan 2005
Location: San Juan Capistrano
Yes, replacing the old clutch fluid is worthwhile, and as sloboy89 writes, it isn't difficult. The only circumstance I can think of where doing this procedure would be "open up a can of worms/potentially doing more harm than good" would be if the bleed screw on the slave was rusted in place, causing it to shear when you tried to back it out.
You can save a little time by using a turkey baster to remove the cruddy fluid from the clutch reservoir (*). Take out as much as you can, re-fill with new fluid, and bleed. It shouldn't take long until clean fluid is coming out the slave cylinder.
*) Make sure not to drip any brake fluid onto your car's paint - the stuff makes great paint remover!
San Juan Capistrano, CA
'63 Guilia spider
'65 Guilia Sprint GT