T-SQL (SS2K8) :: Detect / Determine Data Stored In Varbinary Field

I have several tables a varbinary column in a database. They have names like CSB_BLOB or OBJECT_BLOB. Now I am having intermittent success with getting the data out.

For example this query returns readable text from this data.

0x46726F6D3A20226465616E6E6167726.....etc --data as stored in the column

SELECT CAST(CSB_BLOB AS VARCHAR(MAX)) AS 'Message' FROM OBJECT_BLOB

However this column has the following query results.

0x0001000000FFFFFFFF01000000000000000C....etc. --data as stored in column

--this query returns empty result

SELECT (CSB_BLOB AS VARCHAR(MAX)) AS 'Message' FROM CSB_STATUS_LOG

--this query returns no change???

SELECT CONVERT(VARCHAR(MAX), CONVERT(VARBINARY(MAX), CSB_BLOB, 2), 2) FROM CSB_STATUS_LOG
0001000000FFFFFFFF01000000000000000C....etc

Obviously there is a difference between the two but I am not educated enough to interpret this difference. What do I need to learn / read so I can look at the data in one of these BLOB columns and know how to convert it to something meaningful?

Something like:

1. Try to cast as varchar to see if it is text.
2. Turn into a byte array and see if it is a jpg
3. Turn into a byte array and see if it is a pdf
4. Convert it to hex and then cast as varchar
5. etc....