Yes - but unfortunately - since the process requires an agent - the bar is still very high for a first time author to get a fair assessment. I have sent out quite a few query letters to agents who specialize in non fiction and virtually all of them respond with a form letter and of course they do not bother to ask to read a chapter or two to evaluate it. So until agents wise up and make the connection that a lot of conservatives buy books and publishers like to make money - I guess they will continue to represent authors who sell those wonderful and very important works on specialized topics that no one wants to buy!
I would like to assure you that agents buy books they believe will sell, at least to some degree to make their effort worthwhile. It's true that agents will often not take on a book they don't care for - which can mean a lot of things, but also they feel goes against their own personal beliefs. This isn't wrong; it means they're not the agent for that work. Someone else is.
If the work is great and has something important to say, someone will pick it up. If you've gotten no hits on your query letter, it's time to vastly improve your query letter. That or you've written a bad book and blaming the "liberal bubble of New York" is just the beginning of your problems. Either one. Glenn Beck would probably get going if I had a chance to prod him on the liberal media bias and NY liberals, but Simon and Schuster publishes him without batting an eye and damn, does he sell a lot of books.