That's pretty crazy. I've been on reddit since its inception and have never been banned from pics despite having posted on all kinds of unsavory subreddits over the decades.
I don't think I post in anywhere unsavory... they ban from very savory subs they don't like. e.g., if you post in r/redditachievements you are cooked.
Try posting in /r/conservative, I replied to a comment there once and received a bunch of bans from other subs shortly afterwards.
It doesn't matter what you post, just the association with that sub is apparently enough.