Are Portable Air-conditioners inefficient?

I hear and see a lot of hate and misunderstanding about portable air-conditioners where people try to divert other people from getting them. If you know how it works and how to vent the house properly they work great. Dual hose ones are better in the case of negative pressure, but who doesn't want that humidity,heat and dust from the other room to be sucked out and have the whole house cooled and dust free?