Don't forget about the smell created from a leaky roof-vent.  If you have
the factory two-layer plastic vent and it is cracked, it will create a sour
milk smell when it decides to pee on your carpet.  Water gets between the
layers and ferments.  I replaced mine with the heavier, one-layer
replacement style and that smell is gone.
                                                        Jay
                                                        '85 Westy