To folks outside the lobbying profession, they often suggest that by taking a legislator to dinner, the lobbyist or the legislator is doing something wrong. Just like a family sitting around the dinner table, it's often over a meal that some of the most productive conversations occur.
I've taken legislators to the finest restaurants and to McDonald's and the intent is the same regardless of where the meal occurs. By sitting down for an extended period of time face-to-face, you and the legislator are able to communicate more effectively than in the halls or in their offices where there are numerous distractions.
In all honestly, most of the time I spend with legislators isn't spent talking about my clients or the issues, it's spent just being social. A lobbyist who spends all of their time talking shop, will probably bore a legislator to death. Legislators hear from dozens of people all day long on their pet issues. Occasionally they want to talk about other stuff. Over a meal, you can cover a range of topics much more effectively.