Trolling can be very effective for targeting largemouth bass when they are deeper, however, the percentage of anglers that troll for bass is very small.  Find the deep water weed edges, deep points and shorelines with nice drop-offs and troll with your favorite medium depth and deep diving crankbaits and you should be able to catch some nice bass.
The summer and late fall are usually the best times to fish this way for largemouth bass.