I am part of an online writing community called Zoetrope.com
It's a great resource for an aspiring writer such as myself - I post my stories and receive feedback, as well as giving feedback of my own.

No matter how much I may dislike a story, I can always find something positive to say and write my criticism constructively, so as not to personally offend someone.

But today I wrote a critique for a story that I didn't much care for. There were some good things about it, but the ending was sloppy and rushed. I think the author got bored and finished it quickly. I pointed this out (in nicer language than this)

well, the writer emails me back and says thanks for the suggestions, but that he didn't agree with me (and that other reviewers' thoughts backed him up) and that his story was honed for a "well-read" reader and someone who is intellectual enough to understand his purpose in writing the way he did. Some bullshit like that. And he was going to pretty much disregard my comments as he thought his story spoke well for itself.

I couldn't let that go, so I responded: "Are you suggesting that I am not well-read? If you don't like to receive suggestions, then why post your story to this site?"

he responded that he liked suggestions, just not mine.

It's fine if you don't agree with me, but be classy about it. Insulting me and my opinions is unprofessional and immature (I don't think he could handle criticism well - ok I couldn't handle his criticism, but he criticized my intelligence and reading ability - BIG difference).

Giving criticism can be even harder than receiving it.