"Well," I say, examining the page in front of me as if it would morph into a decent story, "I'd like to see more about the main character's relationship with her father." Glance up. Everyone in class is looking at me. "I'm really interested in it." (Translation: The characters are bad, so please give them background and make them interesting.)
Another boy glances down at his copy. "I don't really like the dog. I mean, I like dogs, but this one doesn't seem very . . . dogish."
I cringe. Couldn't he have said it nicer?
Most people are able to tell when something is wrong. The plot is flat, a character falls short, the setting is hackneyed . . . problems are easy find and point out. It's easy to be critical.
What makes a really great critique, and I've said this before, isn't being able to find flaws. It's being able to fix them. I, personally, go out of my way to point out flaws in a positive way. The setting of a sci fi thriller is a backwater swamp in Louisiana where everyone chews on toothpicks? Say, "I love what you're trying to do here, mixing genre. I'm wondering, though, if it wouldn't be better to put the backwater swamp on Mars where everyone was killed off by a swamp plague, and your main characters crash-land there." It doesn't have to be pretty. It just has to move them in the right direction.
That, at least, is what I do for people who seem to be more clueless than a fat woman trying on a size 4 dress. Give a nudge in the right direction. Or several nudges in different places (plot, character, grammar, etc).
The hardest thing to critique is a story with a plot that is juuuust dumb enough to make you cringe but just good enough that you can't say "You really, really shouldn't write this," like I would have told Rick Cook if he'd ever asked me what I thought of his book, The Wiz Biz (I really can't believe he made sequels). I usually just give as much feedback on their characterization and style as possible and hope that they grow into something better.
The point of a critique is to be honest and fair, to tell the writer what they're doing wrong so they can fix it. The beauty of a great critique is to be honest and kind, to help the writer find the best way to fix their writing. Yes, it takes more energy, but I also think it's a sign of maturity and experience. It is being able to translate "I hate your main character" into "You're trying to make her very sweet" (which is understanding the writer's motive) "but I think it would have more impact" (suggesting a change) "if you made her love one animal in particular to the exclusion of most others" (which is a specific change). Then give your reasoning: "Making her love all animals and children seems a little over-the-top, like a schoolgirl who thanks God for sun, grass, mommy, daddy, flowers, etc. And picking one animal gives you an excuse to expand her background and give her more traits she otherwise wouldn't have had. Like, she loves puppies because a dog saved her life as a kid, and she hates birds because one pooped on her when she was asking out Tommy DiMarco in seventh grade."
See what I mean? Now, there's also the other side of the iceberg, which my method is especially good for. It's the camp of people who only give good feedback and nothing even remotely critical. It's changing "I hate your main character" into "Your main character is so sweet! I love her!" You really, really, really don't want to do this. It encourages bad habits and makes the writer into a worse writer. If it's someone who has specifically told you "I only want positive, encouraging feedback," that still isn't a reason to lie. Just encourage them as much as you can in the things they do well -- whether it's description or setting. I love being able to pick out great lines and read them back to the writer, then look up and see the rest of the group nodding like, "Yeah, I loved that line too."
You don't have to lie to be nice. And you don't have to be mean to be honest. There is a balance, folks, and finding it will make you a better critiquer and a better writer.