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: Basic Instinct
Alternative Character Interpretation: There is much debate amongst fans of the film whether Beth is an innocent victim or an evil Femme Fatale.There are people who think its not a hundred percent clear even at the end that Catherine is a murderess. There is even a theory that Beth and Catherine are in league all along - which explains how they can guess each others actions and know how the same information - and only pretend to be foes to mess with Nicks head. Did Roxy commit any of the murders? Apart from her brothers and the attempted murder of Nick. The final shot is interpreted differently by different viewers. Is Catherine about to kill Nick? Was she going to kill him and then changed her mind? Does the ice pick mean she definitely is the killer or is it only supposed to hint she might be? There is also debate whether the first scene of Nick and Beth in her apartment is sex or date rape.
Interestingly, we never see Catherine commit any overt or violent act (apart from scratching Nick during sex). Both Beth and Roxy act with violence toward Nick, but we only see Catherine remain passive throughout the film.
Fridge Logic: The pantyless scene has become a trope in itself over years, lampshaded, exaggerated, imitated, parodied, nearly qualified for being aDead Horse Trope, and yet it doesn't make any sense in context. Real police detectives are trained to be tough and hardened men with plenty of interrogation experience, and yet all of them seem stunned by a nearly-childish trick (though considering what kind of a person Catherine is and how the story shows that even the most hard-assed man can be swayed by a woman, this actually makes a lot of sense).
Complete Monster: Catherine Tramell is a multi-millionaire sociopathicFemme Fatale who manipulates and kills people for thrills. Her only known source of joy is derived from taking increasingly bigger gambles to defy death, orchestrating complex schemes to assert her dominance. Catherine is a Black Widow type of Serial Killer who seduces people to fall for her, both men and women, before killing them when she grows bored of them. As a published crime novelist she consorts with known murderers to get inspiration and writes Roman à Clef books about her own crimes to prove that she can get away with it. She killed her parents in a mysterious boat explosion, killed a professor at Berkeley, hacked her boyfriend Johnny Boz to death with an icepickduring coitus, killed detective Gus Moran, and considered killing her new plaything Nick before deciding that she wanted him as a sex toy just a bit longer. She manipulates her lesbian girlfriend Roxy into getting herself killed in a jealous attack on Nick and sets up her old acquintance Beth to take the blame for the series of murders and get shot by Nick. Years later in London, she's still doing this with no sign of stopping or regret. When Catherine is set up with a court-ordered psychologist named Dr. Glass after another "accident", she plays mind games with him until she kills Glass's ex-wife and manipulates him to kill a rival psychologist. She frames him for both crimes and gets him committed to a mental institution for life. Catherine smugly informs him that she's used him for another one of her novels and admits that she's always been pure evil and likes it that way.
Evil Is Sexy: When it's played by Sharon Stone, anyway. Roxy also qualifies for this trope.
Hollywood Homely: Brown hair, brown eyes, glasses, sensible, drab-colored clothes (and presumably underwear as well) as supposedly enough to make Beth the plain alternative to the glamorous Catherine though she was still considered desirable enough to gain the sexual interest of Catherine and Nick, do a nice topless scene, possibly have made Catherine obsessed with her and possibly have seduced and killed Johnny Boz.
The Untwist: Catherine was so obviously telegraphed as the killer that most viewers believed it when the evidence began pointing to Beth. The filmmakers stated they had to add the last shot probably revealing Catherine as the real killer specifically to lead people in the right direction.