The term white, typically applied as a description of the slider colour, has different meanings depending on the type of switch being described.
Most "white" switches use unpigmented plastic for the slider. From a scientific perspective, such objects are held to be "colourless" due to the method by which they appear white. Colourless plastic is translucent. The term "white" is unscientific, but for the most part serves as a reasonable simplification for ease of human communication.
Switches with white pigmented plastic show as a much brighter shade, and holding a switch of each type side by side makes this abundantly clear. Few switches use white pigmented sliders, with Marquardt Series 6184 being a notable exception.
The confusion arises when a particular manufacturer uses both unpigmented, colourless plastic, and produces switches with white pigmented sliders. Two brands are known to have done this:
The term "white" can be used to describe both pigmented white and unpigmented colourless plastic, depending on the brand. The term "clear" to refer to unpigmented plastic is largely if not solely confined to Cherry switches; normally a switch is described as "white" regardless of the presence or absence of pigment. "Cherry MX White" itself refers to three different types of switch, two of which are in fact not pigmented.
No resolution to this discrepancy exists. The term milk is used in Asia to denote pigmented white Cherry switches, but there is no current indication of any universal will within the keyboard community to rename switches on a large scale in order to provide consistent colour terminology.