[SDPhantom]

This is how I would implement a fallback list using multiple ors.

watchedFactionID = watchedFactionID
    or (inInstance and hasDungeonTabard and tabardID)
    or (lookUpSubZones and (citySubZonesAndFactions[subZone] or subZonesAndFactions[subZone]))
    or (inInstance and instancesAndFactions[whichInstanceID])
    or (not lookUpSubZones and isWoDZone and bodyguardRepID)
    or (not inInstance and zonesAndFactions[uiMapID])
    or self.fallbackRepID

Note parenthesis are highly suggested to direct which order you want logic operations to run as mixing and/or operations can lead to unpredictable results.