Literary agents have a very keen sense of smell, and their desire to find good things is endless. They are well aware of the dynamics of the literary world, and their main job every day is to figure out what kind of works sell well. To this end, they track all large newspapers and literary magazines, read a large number of critical articles, and communicate privately with writers, editors and other people in the publishing industry, and obtain various internal news in this way.
The emergence of literary economics poses a threat to publishers supports the main point above.