Basic Trope: Bad people tend to be into fetishism and BDSM.
Straight: Villain Bob dresses like a fetishist or is into BDSM; no non-villains are shown to dress the same way or have the same interest.
Exaggerated: The villain is only villainous because they want new people to dominate and torture sexually against their will.
Downplayed: Bob is a jerk who is into bondage and inconsiderate to his partners and their enjoyment.
Justified: Bob's behavior is caused by him being a sociopath or general bastard, not him being into kinky stuff, despite a lack of showing examples of non-bastards with the same kink. Alternatively, the show keeps parroting outdated psychoanalytical theories or similar in order to establish its position as "scientific".
Inverted: There are two very different ways to do this. One is to make sadomasochism a sign of being cool. The other is to make being into only vanilla (non-kinky) sexuality a sign of being a bad person.
Bob's interest in BDSM make Alice and/or the audience wrongly believe that Bob is a bad person.
Alternatively, Bob is acting abusively and tries to avoid blame by invoking prejudice about BDSM to portray himself as a victim. However, it turns out that the people around him have a far too good grasp on Safe, Sane and Consensual for that stunt to work.
Note that using BDSM without implying that either character is evil is not a subversion, it's just Casual Kink.
Double Subverted: It eventually turns out that he's a real bastard after all.