The problem with this issue is that what's going on is secret, so everyone says it doesn't exist. There have been rumours in the past, for example, of corporations using retired executives who were no longer employees of the corporation to do their lobbying, so it didn't have to be registered. They were being paid a pension, but they weren't being paid as an employee, and therefore did not have to register those calls, even though they might have spent more than 20% of their retired time doing it.
On February 9th, 2012. See this statement in context.