So the manager can be honest, but it is usually not even his call. The company will likely to put a lot of value on the maintenance side (which bring the money)

So the manager can be honest, but it is usually not even his call. The company will likely to put a lot of value on the maintenance side (which bring the money) and less on new projects (which get postponed if there are any issues in the maintenance side). I do not think that the manager is lying to you. TODAY he see it as 50/50. But what happen if the cluttered project is late? What happen if there is a need for new features in the cluttered project. I would accept the job only if you are ok staying in the cluttered project team for at least a year or two.