Without demos to tryout, all you have to rely on is pre-release reviews or, if you can wait long enough, reviews from those who actually bought it and played it. This is only speaking for PC though. Consoles don't have to worry about this since I can go to my local video store and rent it for $7; if I like it I buy it. ...And then everyone wonders why publishers are moving towards consoles.
Concerning the relationship between publishers and the media, this is business as usual. The publishers spend a lot of money and time on a product and then pays the media to advertise it. Hopefully this apparent breakdown will force the publishers to start putting out more demos since they're not able to fully rely on pre-release reviews. The other option is to decide not to develop for the PC at all and push consoles. Of course, there are more ways to advertise than just relying solely on a group of reviewers and then complain when they review it poorly, that's just laziness on the side of the publisher.