I bought the Hjerim in Windhelm and didn't have any money to upgrade it at the time, fine no problem I'll just go in the house and store my stuff in MY OWN treasure chest that comes with the house.
So, over the course of time I store like at least 10,000 bucks worth of collected items just waiting to be sold. And I've got about 5,000 in my pocket. Good time to upgrade my house I'm thinking. I go see the steward and pay for a house cleanup, weapon room, bedroom and living room then go to my house to cash in some of my collected treasure.
But... apparently my treasure chest isn't mine and is considered part of the house cleanup! WTF!!! The manual actually says that stored items in your purchased property will not disappear! Unless of course you consider a treasure chest in your purchased Hjerim home to be your property.
Buyer Beware!