If we go by the standard definition of the word ghost, then any possible encounter with an apparition, shade, specter or whatever you may call it will likely not be a loved one.
Why? Because anything out of the ordinary that appears in a human like form with probably some degree of illuminating characteristics are generally termed as ghost by all. This goes to show to a degree that we actually can not say for sure if that thing is a ghost or not. How then do we consider that thing as our loved ones giving our limited knowledge and experience on ghost.
I've read about different cases where people were said to have had encounters with ghost. In saying so, I want to agree with @grecy095 below who stated that certain energies are present with us which she believes to be that of our loved ones who passed away. This can probably explain to a certain degree situations where few people have had encounters with the ghost of their loved ones, if it really was a ghost.