Why does house smell stale?

[realitychick]

It's better than it was, but still driving me nuts.

If I call by other people's houses unexpectedly I'm always struck by the gorgeous fresh laundry smell.

I do 2-3 wash loads a day, mop floors, steam cleaned the carpets, bake cakes, have windows open, change hoover bag often and still when I unlock our front door there's an unmistakably stale, grannyish smell to the house.

I really want the house to smell inviting. What can be causing the smell?

Do you have damp somewhere perhaps?

We might have. Noticed some dark patches in kitchen recently and in the front bedroom. If that would do it, guess we'd better call in a builder to take a look.