These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Cat Lady
Acceptable Professional Targets: If this game teaches you one thing, it's that you can't trust psychiatrists and pest control workers. Oh, and cops are idiots.
Doomed by Canon: Word Of God confirms that this game takes place before Downfall. Seeing as how Joe slaughters everyone in his apartment building, that might include Susan. On the other hand, doubtless Susan is pretty Genre Savvy by now, and besides that, she knows that Joe in particular is violently insane. So it's just as possible that she escapes.
Fridge Brilliance: It only makes sense that the Parasites flock around Susan: she lives in a rough part of the town, she has no friends, her entire family is dead by the beginning of the game, she is unemployed, her few neighbors would be happy to see her gone, so nobody is going to miss her and look for her. She is also very weak emotionally, making it easy to win her trust. She is a perfect target for any criminal.
Fridge Logic: Everything about the Joe Davis sequence. Did he and Susan have a shared hallucination? Was Susan somehow transported into his inner world? Were they in some sort of alternate reality? What was that?
Nausea Fuel and Nightmare Fuel: There's no point in listing the examples because a) they all are major plot points and b) the game consists almost entirely of such examples, with the exception of few Breather Episodes here and there.