Can mean many things, including when something is messed up, fucked up, or ugly.
It can also be used in a positive way, such as when something is brilliant, amazing, extraodinary, etc. Works well when describing movies and TV shows.
It's possible to use "bitched" in a negative-positive way, or in a compliment inside a diss. See examples.
Can be interchanged with biznatched, but not biotched, because that sounds retarded.