What spoils the conference for you?

Preparations for the launch of the conference programme are on the way and soon you are able to see what has been planned for participants and get registered before all the places are booked.
Meanwhile we have thought of possible things that can ruin the conference spirit, so that we could avoid them. Here is the start of the list, hope you can add more to it:

damaged heating conditions on the place

too tight schedule

bad interpreter - reading directly from the documents

presentations do not have any red line, only formalities

speaker is too fast or too loud

speaker not answering to the questions from the audience

during the conference, you do not see anything of the host city

participant list not up to date

no professional use of computers

photographer blocking the view

...