I'm wondering this would be a problem with white frets ?!

I believe only if you smoke indoors

I've aqcuired a number of stuff where that problem was evident on black frets. Over the drivers, the air moves in & out more than elsewhere, and the dust gets caught... most became quite nice with a thorough wash, though.

I'm smoking indoors but I have black frets !

Once when they become like this it is really difficult to clean it. I'm trying to avoid this by cleaning them once in the month wit vacuum cleaner - very gently ....