If you hide some faces on a model with H-key and then select a face loop that includes faces you just hid, then the hidden faces are selected too. If you delete the selected face loop and then reveal the hidden faces on the mesh, you can see that the entire face loop was deleted, even hidden faces.
Is this proper behavior for face loop select? Edge/vertex loop select does not select hidden elements on the mesh, so I would expect consistency on this. I also could imagine deleting faces unknowingly if they are hidden.