What would show that?
You can get hotspots by holding the brakes on at traffic lights.
If the disc is very hot, part of the pad can be deposited on to the disc (you would see the shape of the pad embedded onto the surface).
Then what happens is when you brake normally the pad will grip on the deposit first, then the cleaner parts of the disc, causing uneven braking. This would be more likely to occur with cheap pads though.
It's another 'possible' cause of juddering to add to the list.
If you can see any uneven deposits then there are 2 ways of removing them.
You can either try wet 'n' dry paper in even circular motions, or take the bike out and do some heavy braking and try and burn them off.
Problem is, if your judder is being caused by something else then none of this will help anyway.
If you have sticking pistons on one side of the caliper, so the disc is only being pushed from one side, then that can obviously cause issues as they will be trying to bend the disc which will be flexing. Another 'possible' cause of judder.