Whenever I'm serious, I tend to be blunt. Straight to the point. Uncompromisingly forthright. It's probably a cultural thing. I'm Dutch. Nondutch are often taken aback. Online this only gets aggravated. Even fellow Dutchmen are sometimes taken aback.
Whenever I give critique, I'm serious. You do the math.
Here on deviantART it's mostly a popularity contest. It's all about ego boosting. Critique isn't about ego. However, giving unsolicited critique is basically a direct attack on someone's ego. If I would do that, it would be like hitting someone with a sledgehammer. The miscommunication could be profound. I try not to, but sometimes it happens.
Hey, it even happens on conceptart.org, and that's supposed to be the place for honest critique.
So I tend to not give critique, or only very subtly. Only when someone explicitly asks for it, and I care enough to invest time in them, do I get serious.
So never ask for my opinion if you don't want to hear about your shortcomings. And reprimand me if I point them out unasked.

Just felt like saying this.