Well there's only so many ways to inform someone that I've re-steemed their post, altho I do try to mix it up and comment on the post itself often.
I understand your efforts, but per your Art of Commenting link, I actually am re-steeming the posts i comment on. So there's nothing spammy or abusive. Mistaking me for a bot would be your mistake, and not because of any wrong doing on my part. Your algorythm might be in need of tweaking perhaps, so it won't flag posts that say re-steem if indeed the post was resteemed.