I tend to only comment on articles that I've read in full, and only when I have something to say.

Sadly SteemIt's monetization system really encourages bad commenting. A long and well thought out comment will use more bandwidth, will take longer to write, and will generally reap less rewards relative to the time put into it. In the time it's taking me to read your article, some spammer has written "plz follow and upvote" on twenty posts and is earning more than I am from their efforts.

When I see comments that are obviously copy-paste spam I have started reporting them to SteemCleaners. Its one of the only effective ways I've found to fight the platform's spam problem, and I get a dark satisfaction out of seeing spam accounts getting downvoted and blacklisted.