Mechanical Switch keyboards are much more well constructed compared to their membrane counterpart, however due to manufacturing process variations, sometime we would encounter some slight issues that are within normal specification, and will not affect the functioning of keyboards.
Problem: Clicky Switch (such as Blue/Green Switch) not clicking loud enough
Background:The Blue/Green switch clicks by way of a small white plastic inner slider that, as the key reaches the activation point, is suddenly forced downwards, and as it strikes past the leaf spring, the click is produced.
(The click sound is produced as soon as the leaf spring clears the ramp on the inner slider, not from the slider hitting the bottom of the switch housing.)
As to why some switch does not produce as sharp a click, it might be dust that got stuck and prevent the inner slider from rapid descending. Take the key cap off, depress the switch, and use a can of compress air to clean out dust.
Otherwise, it does not impact keyboard functioning, since Cherry does not monitor clicking sound level during manufacturing process, and has no away of doing so.
Photo comparison of the Blue and Brown switch
Problem: Key feels scratchy/ Switch does not feel smooth
Symptom:When pressing the keys, would experience some slight friction near the side of keys, it would be more obvious with the key cap on.
Compare switch with others on keyboard. IF they all feel the same and the keyboard is new it is not a defect. Perhaps the keyboard will "break in" as the factory fresh plastic/grease wears.
Otherwise, this is not a Switch quality issue, it is due to unequal pressure distribution after the key cap is fitted.