Son Toshi
I made the mistake of putting my stuff in a house that wasn't mine on and old saved game, the ship in the Imperial city with the pirates. I killed them all then I'd store my stuff in chests in their ship and one day I came back to find all of it had disappeared except for the default items in the chest. But as for as houses you own Idk it's never happened to me
If you use Captain tsauds chest then your things will be fine as that container's contents do not respawn, however any other conatiner will respawn it's contents generating new ones, and getting rid of yours.
All open topped sacks and torn sacks in Cyrodiil are safe containers, such as the torn one at fort nikel just west of the imperial city, allowing you to use that as storage and live there.
all containers in any house you have purchased, or have the deed to will be safe containers.
The dead drop locations are safe containers, but possibly only after you have completed the quest related to that dead drop.
Shadowmere can be used as a traveling safe container, simply knock him out to store things on him, or retrieve things.