Thanks for the question, but I have to disagree with one of the answers.
I have a number of offline databases in one of my servers and the following query returns values for all of them
select name, state_desc, DATABASEPROPERTYEX(name, 'Collation')
where state_desc = 'OFFLINE'
I can see that BOL states opposite, but if anybody else want to try and share the result, would be great