He knew the truth. Even if he never outright asked, he knew in his gut that something was off with that scumbag. It wouldn’t surprise me if he was also someone of questionable morals. You are the people you surround yourself with, i fully believe that.
All the letters have one thing in common though: they’re overly saccharine and suspiciously dodgy (actually that’s two things, sorry). It’s like they’re trying to describe a modern-day Beaver Cleaver.