Summary

When listing Exits, Rooms should use either a proper name of the exit, or the directional if there is no proper name.

When look-ing at an Exit, the Exit should either return a description, such as being a door that is closed, or the description of the room that the exit leads to, if available.
This description should be modified by the exit, for instance:

Peering through the open door, you see:

Dingy Hallway
A dingy hallway, with a rug in the center of the room...

Possible Solutions

Rooms should check each Exit for a db.proper_name field - if it's not set, the Exit should be referred to by its db.key value. The reason for this distinction is that generally, the exit key should be one of the directionals, not a proper name.

Another Option

Perhaps the Exit could default to using the first alias set?

When a character looks at an Exit, the Exit should return the description of the Room the Exit leads to. This could be modified by prepending text to the description - for instance, a character might "peer through" a door.
In the case of a door, hatch, or other closable Exit, potentially a character may see said closed exit instead. Each typeclass should handle this logic.