As best as I can find from Maya's documentation:
"Intermediate object ... specifies whether the dagNode is an intermediate object resulting from a construction history operation. dagNodes with this attribute set to true not visible and/or rendered."
This script will track down Intermediate node types and select them for you.
Enter the command:
The script will issue warnings for any Intermediate objects if finds; e.g.
// Warning: polySurfaceShape3 is an Intermediate object //
The script will select all nodes reported as Intermediate objects.
Open the Hypergraph
Graph -> Scene Heirarchy
(This mode will be unavailable if the Hypergraph is already in Scene Heirarchy mode)
Options -> Display -> Shape Nodes
Options -> Display -> Invisible Nodes
Edit -> Show Selected
View -> Frame Selection
(If nothing frames in the view, it's possible that your selection was canceled by a rogue mouse-click in the Hypergraph window; try running findIntermediates again.)
You should now see the highlighted Intermediate objects displayed in the Hypergraph. Delete them, edit them, whatever, at your whim.