That will be mould - pull out the soap drawer and give it a good hot wash in the sink with some bleach - scrub the spots away.
Biological washing detergents permit cooler 40° washes but the bugs don't die at that temperature - the bugs grow and fester inside the pipes and that may be the smell you notice.
Run some hot washes now and again to kill the bugs - run a wash programme with no laundry and use some vinegar instead of detergent.
If you have a drains inspection pit close to the house then lift the cover and check inside - "stuff" may be backing up.
Peccavi, February 2013
