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.
Evil Is Cool: Played with. Parker is undeniably a badass, but the "professionals" he works with often wind up dead and Parker himself can find himself stripped of a stake.
What an Idiot: Westlake will generally take some time at some point in each book to illustrate what an amateur would do in a situation, and why it's a bad idea.
This is taken to new heights in one of Westlake's Dortmunder books, which alternates between the crooks reading a Parker novel with a carefully executed kidnapping, and the thieves in "real life" screwing up the plan completely.