So the simple definition of the depraved bisexual is a couple of things.
1. they are someone who is a murderer, evil, or some sort of criminal activities and is bisexual.
2. their bisexuality is stated as one of the reasons that they are depraved; and they sometimes play this up.
Here are some characters from tv, films, comics, and more that would be classified as the depraved bisexual.
Interesting note - most depraved bisexuals in media are white women, you decide to what to do with that info.