When symbolizing by "Unique Values" in ArcMap, if a domain is present on the column the the values in the domain are added. If there is no domain the table is scanned for unique values in the data. *If there is a domain but it is out of sync with the actual data only the domain values are added. The other values are listed as "all other values".
We have a large published geodatabase that is replicated from our edit GDB. Although we can repilcate data, syncing domains is much harder due to object locking in ArcSDE.
We have a large user base that occassionally catches that something is missing, at which point we either update the domain or drop it from the published GDB.
I think it would be useful to have a lilttle radiobutton on the Layer Properties - Symbology tab what would allow a user to specify something like "base on domain" or "scan table for values".