I find I am spending a lot of time lately examining lists of proposed indexes that were generated by an index tuning adviser or some other automated process.
Back in the day (circa 2005) I found the suggestions to be rather awful in that they seemed geared to one specific query and more often than not were merely a covering index that had every column in the table whether or not those colums were already indexes.
As time has progressed, I feel the index tuning advisers have improved dramatically, but I still have a built-in mistrust and still want to spend the time to review each one.
I am trying not to be pessimistic, but it is difficult when a vendor (Microsoft) suggests to add multiple overlapping covering indexes to improve performance, especially when we are paying for storage space. I also don't want to spend my own time needlessly. I would rather be fixing poorly written queries.