Because people tend to have their own favourite citation key scheme, we allow aliasing: a locally maintained file that gives for a local citation key the corresponding citation key in the remote database.
A properly set-up remote BiBTeX database should list predefined strings and conference proceedings in separate files, one for each citation style (e.g. for long - "Journal of the ACM" - and short - "J. ACM" - styles).
Secondly, the way the information is entered in the BiBTeX database may not be complete, or may not be completely what you want (e.g. you prefer to list the location of a conference in the address field of an InProceedings or Proceedings entry). This may be mitigated somewhat by implementing a local substitution table, or by using only the on-line strings and conference databases (saving already quite some trouble).