Washer Dryer Laundry

Washer Dryer Laundry
What could be causing the musty smell in my washer/dryer laundry room?

I have checked for and found no water leaks from the washer or water supply lines.

Clean out the dryer Vent- ***I don't mean the filter screen***

That would be too easy to figure out. I mean the actual vent leading out side. most people never have these cleaned out. When I moved into my new rental house this was just the case. It was so clogged it was a fire hazard. There are tools at home depot you can use for this.