Yes, any location can be used as either a pickup or drop-off location. The classification of Pickup Location or Dropoff Location only really indicates what it is most frequently used as to shorten the result lists when using the Location Locator when building orders.

Q: How would one tell if these are set up correctly?

A: Common Locations for OEMs usually use code table entries to specify their location identifiers (Port/Railhead Code, SPLC Code, etc).