Handling bad imports
Handling bad imports is hopefully not going to be something we'll have to do very often. Imports should not be carried out very often, and when they are, they should be carried very carefully in accordance with the Import/Guidelines. If someone fails to follow this, then that's something we have a right to be annoyed about, however...
The procedure would be something similar to handling Vandalism. This includes "assume good faith". In the first instance we must assume that everyone is at least trying to make the data better. As set out in procedure for Vandalism, you should start off with calm discussion rather than angry accusations.
As with vandalism, you may ultimately decide to contact the Data working group for resolution of serious import related issues however this only comes after community resolution procedures have failed.