Two are blatantly and brazenly corrupt. Four are right wing shitheels who while they may have a ludicrous interpretation of the law, do actually have it and hold to it (hence opus dei member Amy Coney Barrett ruling in favor of gay marriage, for example because she believes that marriage is the fundamental structure of social life).

Of the infamous six, you can absolutely get a democratic majority to impeach Thomas and Alito, but Roberts, Barrett, Kavenaugh, and whatever the other one's name is are more difficult.

Personally I want all 9 investigated for corruption, there's just too much that's blatantly there to not do so.