any electrical geniuses out there?

[Livolsi, Stephane]

Basically I am looking to confirm a suspicion....

As I understand it, there is always 12v applied to the power window mirrors.
When you hit the switch, it goes to ground, completes the circuit and the
motor runs.  When you let go of the switch, the circuit is broken and motor
stops.

Now, if all 4 window motors are slow (let's assume they aren't all partially
toast) would that indicate a common poor ground point somewhere?

Stephane