Are there cases where a good agent can sell a book that a bad agent can't? What are some of the signs that your agent is the problem and not your manuscript?
If the manuscript isn't even getting read - ie, the agent can't get editors to agree to read it or it languishes unread for ages on editors' desks - then it *could* be the agent. A good agent will know how to: (i) pick the right editors for the project, (ii) pitch the book to them in a way that will make them want to read it, and (iii) actually get the mauscript read in a reasonable period of time. And even great agents sometimes have manuscripts that languish, depending on factors outside the agent's control - like an exceptionally busy editor/house.
If it's gettiing read but rejected, there's a chance it could still be, at least partly, the agent picking the wrong editors to pitch.
But if the manuscript *is* getting read by the right editors, editors who might be interested in the manuscript, but those editors keep passing, then it is likely the manuscript, and not the agent.
~suki