I'm seeing bad CnC everywhere.
Seriously, if there's something wrong, SAY IT.
Don't just say "it sucks" because THAT DOESN'T FUCK HELP YOU DIPSHIT.
Don't fucking assume what it is. ASK BEFORE SAYING ANYTHING.
If you're going to give CnC, at least say something good about it. If the whole thing is shit, just tell them "hey, you might want to (insert fixes here)".
Good CnC:
The lighting is a bit off. You may want to move it somewhere else. And there are too many C4Ds. Get rid of some.
Bad CnC:
It sucks.
If there really is nothing good to say about it, just suggest a tutorial. Maybe two.
If they don't have the necessary tools, help them out.
Get the picture?