These caught my attention in particular:
“Your sidekick, if you have one, is a lovable doofus.”
Okay, Archie Goodwin was not a lovable doofus. Neither, for that matter, was Dr. John Watson (or Marshall).
I think the “lovable doofus sidekick” trope can largely be traced to the late Nigel Bruce, who played Dr. Watson in many Sherlock Holmes movies and radio shows. His Watson was definitely a doofus (“lovable” is a matter of taste), but it is not canonical.
“You often will let innocent people remain in prison, despite possessing exonerating evidence, until it serves your purposes to have them released.”
Jan Sleet has never done this, as far as we know, but she totally would.
“Everyone that you meet has at least one dark secret.”
It was a maxim of Nero Wolfe’s that everybody has secrets, and everybody lies. Finding out who committed a murder is not about figuring out who is lying or hiding secrets.
I don’t think Wolfe ever said this explicitly, but his general premise was, “If all that was needed to expose a murderer was to figure out which suspect is lying, then anybody could do it. You wouldn’t need a genius (like me).”
(Wolfe would have said it better, of course.)