I encountered foamy fluid when changing the accumulators on my wagon. The bleeder valve was well stuck in the valve body, so I cracked a line at an accumulator an took a shower. The accumulators were shot, as a pencil poked into them would go down well past the top of the sphere.
After all was buttoned up, there seemed to be no need to bleed the system as it worked as the guys back Sindelfingen intended.