I've got a few outlooks and techniques of my own, some of which seem to help.

Including Information about the renders I post:
I usually post whats going on in the image I render or what I'm trying to achieve, or a little backstory, or usually what's going on in my life that came about into rendering the image. This is important to me as without any one of those catalysts, the render would never have came about, or the particular mood / feel / theme of the render. So I provide a few sentences or a reasonable paragraph (or two). If people view the image, read what i've wrote, then they get to understand a little more about what went into the image, why I made the image, and usually leave a nice thoughtful comment, sometimes reflecting on what i've wrote and rendered instead of getting as many cookie cutter comments. 

I'm not the only one who does this, as some of my gallery friends here usually has a story to tell that the image is to depict. Often its a history bite, with an anecdote of world history and fact. Whatever it may be, I often also see that people also tend to leave thoughtful comments and feedbck than the generic copy'n'paste.

I also see lots of people, who put up their images and don't offer or say a word about their work or what the image is about. Sometimes not much or anything is needed, sometimes the title says it all. Although I do have a few friends that do this, they put their image together in a way that its not a pinup, but rather in a silent movie type style that makes you wonder and guess.

Understanding the commenter:
As a few mentioned above here, theres usually a good chance that one doesn't realize that the commenter isn't always the same nationality, but from a different nationality with English not their primary language. Usually viewing their profile and gallery you find out those things.

Including my own thankyou:
I also usually add at the end of the image my own little cookie-cutter "Thankyou for viewing. Comments, constructive criticism and opinions are always and especially welcome." style thankyou card line. I do it to encourage commenting of all types, even though I really value and hope to get thoughtful ones.

Its not just about return-commenting:
I also do my best to return commenting on those who commented on me. I do my best to always browse their galleries, and one a few that I like, I'll leave a thougtful comment on, usually what stands out to me that makes me like the image. Some people really enjoyed my extra effort that I put into writing several sentances or a short paragraph, some of which have become good friends, and honestly comment their opinion on my works. This goes right along with the flipside of when I have a bunch of short 2-5 word comments then someone posts a few sentences which really stands out from the crowd. So it works both ways, along with the old saying - you have to give before (or if you want to / expect to) you receive.

I'm happy with what I get:
So, to me, I'm happy for the comments I get, which anything at all means more than just watching the view count climb. In appreciation I'm also happy to return the favor in commenting. Its certainly better than absolute nothing, and thats what I had came from on over at DeviantArt. (guess I wasn't part of a clique or social network over there. If your not then you'd might as well be stuck out in the middle of a desert, and left desperately thirsting for a comment that'd be like a few drops of water to one's parched throat). And thats directly the biggest contrast that I found when I came over here - when I post an image, theres at least going to be a few comments on it, rather than just a view and a wordless add to someone's fav collection. If someone even says a couple words, it tells me the person liked what I made, and it does feel good.  If I'm having a really down and out lousy day, all I need do is head to my gallery and be reminded people like my work so its not all bad. When I make my renders, I make them knowing they're not perfect,

Take what you like and scrap the rest:
Words of wisdom one of my gallery friends told me in their comment on one of my renders. It means to basically take what you like from the comments received, and don't worry about the rest is the rest isn't to your satisfaction, or different than your expecting. And sometimes people have different reactions to what you render, sometimes if its a different take on a familiar theme. I know at least once, I put up a render and titled it, and not everyone liked or agreed on the title, since the image wasn't what they expected by the title and the itsy-bitsy thumbnail they clicked on. But hey, thats totally ok, as the comment wasn't rude or disrespectful, it was simply the person being honest of what they thought.

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Now, going back to the opening post title "repeat offenders" , I do have a question about one subject of commenting / leaving comments:

Have anyone of you here received possibly a generic short couple word comment, followed by the "please view my gallery" , and get that from the same person several images in a row?

Whats your stance on that? Is that commonly accepted here in the galleries? 

To me it least feels the effort is less about caring what you've rendered in your image but more like a self serving interest to get their view and comment number increased, possibly to climb that ladder. Or am I interpreting that wrong?