Jim, here is my British take: disused means no longer used (as) and I think implies a final condition.

A vacant appartment is still used as an appartment but is currently unoccupied. If it is no longer used or formaly used as an appartment, it is disused.

Obsolete equipment and suplus material may still be used or perhaps sold, in which case it is not disused.

Broken down equipment is presumably awaiting repair...

I would not use disused when reffering to clothing.

Jon