The vast majority of hotels in Copenhagen do not have air-conditioning and do not advertise that they have it, so why do so many complain that hotel's do not have air-conditioning.
Considering that Denmark is in the forefront with it's environmental policies and focus on sustainability - visitor should learn to adapt in the same manner that residents do. Furthermore the mild danish climate does not require installation of unnecessary and costly air-conditioning units.
Yes it can get hot - and this summer was amongst the hottest in man's memory, but why blame a hotel for something that they cannot influence.
Let's appreciate nature for what it is and be grateful that we - as opposed to many others - have the opportunity to see the world.