I imagine we've all been guilty of this at some point or another. A rejection comes in, maybe a harsh critique, we're feeling a little low and all we can think is, "But my mom/ my cousin /my hairdresser/ my garbage man /everyone who's ever read it loves it! Why can't this agent/editor see that the general public would appreciate this?!?"
I've done it. I admit it.
But you know what I've discovered? That's not the point.
Picture the average reader. I actually consider myself an average reader and I'll use that to justify this slightly less than complimentary description.:) The average reader in the U.S. does not read for errors or consciously check out your point of view. They are not looking at your pacing or the way your story weaves so intricately with the subplots. They are reading for entertainment.
(Now, if you have written your story right, they won't have to look for these elements. They may not be able to tell you in all of the above words, but they just know that everything "clicked.")
The average reader will pick up books their friends recommended to them, spines that caught their eye in the bookstore or library, the paperback that was sitting on their friend's coffee table. The average reader will often slog through a boring middle of the book to find out who-dun-it or if the guy gets the girl. (I'm a cheater, if I'm getting bored I will often skip to the end and if the end looks good then I will decide if I want to finish the book and see how they got there.:))
Like the average spectator at the Olympics, viewer at the art gallery, and diner at a five-star-restaurant, the average reader is more easily satisfied than the professional judge/critic/agent/editor asked to evaluate the athlete/art/food/book.
If all of your beta readers are average readers, you will probably get less out of them than if you chose some beta readers from the industry as well. Why? Because the average reader will be more impressed than the average editor. I've heard so many people lately say, "I don't understand, everyone who reads my MS loves it! Why can't I get an agent/published?" People will reference their muse with the same tender affection. "My muse was just guiding this book, why can't anyone see what an inspired work it is?"
Well, the fact of the matter is that neither your average reader nor your muse are acquiring manuscripts.
And would you really want it any other way? What if we held other industries to the simple standard of what their average consumer likes? I know a lot of people who are happy if you simply put a reasonably done steak in front of them. (Hehe, like me when I'm pregnant.:)) I personally love fine food. I am so glad that there are chefs out their working hard to please the food critics. Why? Because it means that I am going to get a very, very nice meal. Now, I don't know what to look for . . . the cut of the meat? I'm clueless. How seasonable the vegetables are? How should I know. But boy, because someone who does know is watching this chef very carefully, I know that when I get my meal, it is going to be just right.
Same for publishing. Find someone, who knows what they're talking about, and ask them not, "did you like my book," but "Tell me what was wrong with my book." Then listen. Really listen.
Like all critics/judges/agents/editors their judgement will not be infallible, but it will probably be better than your average reader.