As a member of the board of my local SCBWI, I got to have dinner with several agents and editors.
Oh, the places we go...
To hear the agents discuss with each other about how they approach queries was enlightening. Without talking out of school, and without naming any names, here are some things I learned.
First and foremost, all of the agents want your book to be good. No one is going through submissions with an evil laugh, happily rejecting authors while making fun of us all. They genuinely love books and the authors who write them, and they absolutely want you to be their next favorite.
Some, don't read your query letter at all, but go straight to the sample. If they like that, they'll circle back to the query. Some, are just the opposite. They feel if you can't sell your own work, you probably aren't going to be a good fit for them. Some pass on word counts alone, others (okay, one, but it was a small sample size) won't even look at a word count. Some expect the first paragraph to be why you picked them to submit to - there was a general feeling that agents want to feel like you've chosen them for a reason, while realizing that it's not necessarily so - others were more concerned with the hook and summary, or the bio - which didn't need to be about writing experience.
In short, it's a crap shoot.
All of them made their decisions based on the words on the page - either the sample, the letter, or both. All of them want a sample to start with chapter one.
And, all of them are very nice. They love books. They love authors. They could all make more money doing less work in some other business, but they've chosen to be in the same business you've chosen. If your image of agents is anything other than that, you're wrong. Sure, some might be mean, or impolite, or rub you the wrong way, (none for me at this dinner), but you have more in common than not. So, cheer up. The gatekeepers don't want to stop you. They want to help you. You just have to show that you're worthy of their time and attention.