I get really annoyed with the forums when I see a newbie post their very first query letter and all they get in return for putting their work out there is, "You're never going to be published. Throw it all out and start again."
I'll give you a specific example: there's a person (I think the poster is a guy, so we'll say he) who just posted his first query on the forum I visit. It was written in the first-person perspective, which is frowned upon by many-an-agent. I mentioned that to him, especially because he said he had a version of that query in third-person.
However, the next person who commented on the letter brought up the author's word-count: 169,000 words. That's a long book, especially for a mystery (fantasy novels are commonly this long...if you have clout behind your name). This commenter told the writer, "That word-count will get you an instant form rejection. Can you cut the word-count?" (He said some other stuff, too, but it's along those same lines.)
I had to ask myself (especially because similar things have happened to me): what does this have to do with my query letter? I'm not looking for a comment on the length of my book. I suck at writing query letters. I need help learning how to do this difficult, important task.
Sure, the word-count may hinder your chances of getting an agent (especially if it's long), but you don't know what's going to happen. And why does it matter to you if the word-count alone will get that writer an instant rejection from every agent he sends the letter to? If he's done the research, he'll know what the industry is looking for, he'll know what the "standard" is, and then he'll make his own decisions from there. In the mean time, let him write the best query possible. If the word-count is ALL he has going against him, then he's still way better off than I am, at least as far as querying goes. He needs to learn how to query, he needs to know what works and what doesn't as far as the letter-writing process goes. He may even get an agent or two to request pages. But even if he doesn't, who are we to rob him of a valuable learning experience?
So, when you're critiquing a query, please comment on the content of the letter, not the length of the novel. His core critique group can handle that bit. After all, this industry is discouraging enough. And as solitary creatures (which many writers are) we've already put ourselves out on a limb asking for help. In the long-run, it'll be more helpful to stay on topic because then he'll be more open to learning from the critiques you give.
Update: Kiersten White has a post that relates. It's all about how aspiring authors should behave in this community... and she tells her readers about some of the consequences of not behaving well.