@irvmull
I suspect that the trolls are too cheap to pay for access.
People who actually pay to read stories are more likely to make rational suggestions.
My experience on the matter has been the complete opposite.
I have found over the years, that paying members are more critical than the freeloaders. My hypothesis is that because they pay, they expect (demand) a greater level of service from both the site and those who submit stories. In that regard I understand their point of view (understand, but not necessarily agree).
A perfect example of this, are the site writing competitions. The scoring is absolutely brutal, and only paid members can vote.
In this situation, I believe the old adage ('Don't feed the trolls') is the best way forward. Over the years, I have noticed that those who moan (and I have been guilty of it myself) about the feedback received in their blogs, are opening up themselves for further critical correspondence.
Read the comments/feedback, delete if needed, and move on.