I recently posted what I thought was a humble and polite comment that I saw the "chopped-off skull" error in someone's work [link] , thinking that if someone told me that, I'd be glad for the help:

"I'm far from the best person to offer critique, so I hope you don't mind me saying this..
Your drawing has the "chopped-off skull" error, which makes the otherwise great drawing of his features look weird.
This picture on someone's art blog might help you see it: [link]
And here's some text about it: [link]

Hope you don't mind me saying it, I just saw it and thought you might want to know.. "

Not so in this case. Here's the response I got from [link] :
"Talkin' bout a "chopped-off skull" error -> [link] or a "head of a size of a pickle" considered to the size of the body -> [link]
Sorry Pal : / This is your work, and if you want to give me an advice or anything else, do it in proper manners, try to get to know me first and intend to be better than the person who you're offering critique to. Now the second thing, I'd say that the size of a skull in the portrait isn't always the same cause it reffers from which perspective you're drawing from. Here I admit I've made a mistake, but I'm satisfied with my skills which I've gained for only a one year or quite even less and that's probably called genes. And let me give you an advice, if you're so good with advices, first look at your work, help your self then help someone else. P.S. Thank you"

Nice, huh?
I tried to reply to say:
" If this is how you respond to someone trying to help you, I'd hate to think how you treat a real critic.
I know my old stuff is really bad , hopefully I'm improving ( [link] ). Nowhere near perfect, but if someone offers me helpful advice, I'll thank them genuinely.
Good luck."

But that user has blocked me. Nice, huh?