"Question: Does it reflect badly on an author (in regards to future deals) to change literary agents mid-contract? Obviously, my current agent is entitled to any monies earned by current and past deals, but I'm wondering how to professionally and ethically switch agents before I submit any more proposals to publishers. I hate that I'm even considering this-- I'm a very loyal person and my agent has sold several books for me-- but this last contract has revealed some ethical issues (dishonesty, missteps) that have made me feel like I cannot trust her. Also, if I were to switch agents, how would I start the process? By contacting the old agent? Submitting to new agents?"
To begin with, read these two posts from this blog, one from 2009 and one from 2010. They will explain a lot. I already covered much of this ground in previous answers:
There are several issues at stake here. First, you need to make sure that legally you are able to fire your agent. You will have to check the agency agreement that you signed with her. Every agency agreement is different. Some agreements commit authors to multi-book and/or multi-year obligations. The most important clause here will be the termination clause, if one even exists. That is a clause which allows you the right to terminate the agreement, and specifies upon what conditions. For example, a clause might read that you can notify your agent in writing and after 90 days notice, the agreement is terminated.
But it is often more complex than this. From an agent's perspective, if an agent is working hard on a book and it is actively on submission and an author for whatever reason decides to fire him, the agent justifiably has to protect himself so that his work is not for nothing, and often there will be a clause stating that in the case of termination he is entitled to commission if that active submission should become successful. And it could take several months for publishers to respond. So there is often some sort of waiting window even after termination.
But after that window has passed, for example three or six months later, and the book is no longer actively on submission, then, assuming your agent allows you to terminate, there should be no reason why the agent continues to be entitled to commission. You don't want to end up in a situation where you terminate your agent, hire another agent, that agent sells your book, and the old agent comes out of the woodwork for commission on a deal that she did not make. Then you are stuck paying double commission. It all depends on what you signed.
Every agent has a different way of operating. Some agents will let you out of an agreement if you simply ask. Others will refuse. Some are litigious; some are not.
As far as finding a new agent, the big issue for them will be whether or not the current work has already been submitted, and how many publishers have seen it. If your old agent has already sent the work all over town, and there is nowhere left for the new agent to submit, then he won't want to take it on. That will be the bigger issue.
Ethically, if an author comes to an agent and tells him he has just fired his old agent, especially mid submission, it will certainly raise a red flag, and he will want to know why. If the old agent has acted unethically, and the author can prove it, then that of course explains it. But if the agent has not acted unethically, and the author is just demanding, then that is a different story and can turn off some agents. An agent's deciding whether or not to take on a book is always a combination of the book and the author behind it.