I'm probably not understanding something but here is the question.
I have done a query on dm_db_index_usage_stats. I've noticed that a couple of my indexes have large numbers (6.5 million and 20 thousand) in the user_lookups column but these also have a zero in both the user_seeks and user_scans columns.
My understanding (from books online) is that the user_lookups column counts bookmark lookups. As I understand it that is when the database can't find all the columns it needs in an index and has to visit the main table or clustered index for the remaining columns. However why would SQL server have done this if it has never done an seek or scan on the index?