Why did that suck? What made it suck?
Haha aw! But it's true, sometimes stuff just plain sucks.

As an editor I've offered a lot of critiques to others, so I know they are important. Professionally I deal with journalistic writing, so different guidelines apply. I've given feedback on fiction, mostly when I come across something that truly shows promise. I've seen beginning writers who have no concept of mechanics, yet their ability to form plot or their descriptions or dialogue seem to come very naturally. That's really fun, to find someone who has such natural ability and it's great to nurture them along.

Mostly I'm pretty hands off, I tend to let others find their way with only a few basic observances. It seems best, imo. When a writer is beginning to find their voice, the less said the better. Established writers are a different story of course, and they often ask for feedback on specific things.

As for commenting on something so outside my purview that I can't connect, or something that truly sucks - I sidestep these.