I once stayed at a Sheraton and noticed the safe was already locked. I called down and the manager came up. I couldn't tell if he entered a code or had a key, but it was open within 10 seconds.
Seeing that made me feel hotel safes are much less secure than I had thought. I still feel comfortable placing cameras and passports in them. But, if I were carrying something worth more than the average house (highly unlikely), then I'd definitely place it in the main safe downstairs.