I wonder if anyone critiques their issue and mails it back to them?
BP has (or at least had) a reader board where we would vote on the covers, content, specific future articles to be considered, etc... a few months before an issue. I participated 4-5 years back via something like Surveymonkey. Got too busy and the surveys quit coming so not sure if they are still doing it.
At the end, there was a place for comments for future/past concerns but imagine they looked at letters to the editor (pro/con) vs. how much a particular issue sold at the newstand, etc..