Within my lifetime, Troy was considered by many experts to be a myth, until it was found. I think it is safest to assume that these things are historical at the core, with the same amount of embellishments used in modern war movies to tell a good story, and to compel support for the right side ( which in those days meant a generous helping of gods). Homer was too good to make it one sides propaganda, though.
On the 1800s Heinrich Schliemann tested his possible discovery of Troy by running around it anc comparing it to Homer.