Kobo screen issues: what should I check new device for?

Hey all,
I just got my hands on one of the last 32GB Formas and Im pretty happy with it, but being an informed consumer I thought I should do my due diligence and check for screen issues, since they seem so common.

So far I've heard of:
- the wedge issue
- yellow tint
- blue patches
- flickering

Are there any others?
What should I look for?

While nothing is really jumping out at me to the extent of making me unsatisfied with the reading experience, I do want to check the device.

I think it may actually have the wedge issue: a 'streak' that is very subtly gray on the left hand side...But VERY subtle. What is the right screen setting to check for this?

It also seems to show a couple of white specs on a dark screen, but perhaps this is dust under the screen protector?