Yes! A long term rising damp problem brings with it certain soluble groundwater salts into the wall; these are left behind as the water evaporates, and become concentrated in the plaster. The largest proportion of these salts are hygroscopic, that is they are capable of absorbing water from the surrounding environment.
As a result, affected plasters and masonry may remain damp, even though the source of moisture which leads to the buildup of the salts has been eliminated. It, therefore, stands to reason that any property which has been subject to a long-term rising damp problem must have some degree of salt contamination in the plaster and the underlying masonry. These salts can, on their own, cause spoiling to certain types of decoration, even in relatively low quantities.
Following the insertion of a remedial damp proof course, a damp wall can take many months to dry out. Furthermore, due to the limitations of chemical damp-proof courses, the wall is always likely to remain damp at the base (this is an important consideration when determining whether a DPC is functioning or not.