The only way to truly clean your electrical power from polluted energy is to completely absorb it, thus removing it from your system. They serve as the first line of defense against power line transient voltage surges. Secondly, they do not offer any protection to transient voltage surges that are shorter in duration than a couple of milliseconds. Regulators cannot protect against voltage spikes because of their slow reaction time. Neither can they offer any protection against voltage transients such as RF and harmonic activity.
Dedicated circuits protect voltage drawn in amps only.
Dedicated lines generally shield out noise-producing electromagnetic and electrostatic interference. They bypass power interruptions downstream of their point of origin. Isolation transformers have been one of the most widely used power enhancement devices, but are fast becoming obsolete. They drastically reduce small voltage fluctuations, and reduce common mode noise introduced into the circuit from multiple upstream ground loops and harmonic activity. They stop lower threshold voltage spikes, but only when tested under unloaded conditions.