As I understand it, the twisty filter bit (I don't know what else to call it) likes to attract grit. And becuase there is no way of cleaning, the grit binds up.

And also, for a single LED system, that thing is HUGE. You could have put in a simple integrated circuit that would have been able to fit in between four LEDs and rotated through them with each click. Or any number of other design options of increasing complication. The filter design just looks cheap.