They aren't holding back info....they don't have it. I have overheard some of the discussions they have had with customers while trying to be helpful and it's quite entertaining. I once listened to the husband tell someone that lake X, which is probably the best multi-species lake in the area, "probably doesn't have any fish in it, except where the river comes in."
Running any kind of retail shop is about serving customers and creating new customers. If all you have to offer is a tankful of minnows and the same lures/tackle as the CTire around the corner, you better have some other way to turn people on to fishing. Local knowledge is one of those things.