The seller lived through the season you cannot see. Ask before you make an offer.
An empty flat produces little moisture and can hide a pattern.
Unheated rooms show the envelope at its coldest.
The same wall every year points to the building.
A room repainted this autumn has not been through a winter yet.
Changes the cold surfaces, and the date tells you how many winters have tested them.
A treatment is a record that the problem was there before.