What the classification says
Mainly dark coloured (class B and C characteristic); lightness alone is not a guarantee of class A.
How to spot it
Compare against a new pallet. Grey or brown weathering is the main difference between class A and class B.
Why it matters
Colour is what most people notice first and what the classification trusts least. EPAL's poster describes class A as mainly light-coloured and classes B and C as mainly dark, but it also says lightness alone does not guarantee class A. So a dark pallet can be structurally perfect and still class B, and a light pallet with a twisted block is not class A.
Effect on the pallet's class
Not a defect. It moves a sound pallet from A to B, but never to not fit for use. See Class B for the full criteria.
Repair
None.