I have a Bosch LogiXX 1600 express machine and the tray where I place the washing powder and softener has become black with largish pieces of flaky material. When I remove the tray the whole of the area behind is similarly.affected. I clean these areas regularly, but can anyone explain what causes this and how it can be prevented.
You probably use non-biological detergent at low temperatures. This provides the ideal breeding ground for bacteria which isn't being killed as it would be if you used bio at high temps. http://www.washerhelp.co.uk/usage_2.html
I've a bosch too and was wondering why the glass in the door and the rubber ring thing was getting dirty on the inside - I'm guessing that's low temps too!