No - there's no good Sith. Sure their actions might cause some good - but their actions are selfish. As about Darth <PERSON>
Darth <PERSON> was part of the Banite Sith Order - which is <PERSON>'s lineage. This <PERSON> organization sought to destroy the Jedi from within via plotting, secrecy, and infiltration - not outright attacks and ambushes against The Republic and The Jedi Order. The Banite Lords' background is kept in anonymity - and you don't have access to their private lives.
<PERSON> is a Banite Sith. And these are the principles of the Banite Order:
"True power can come only to those who embrace the transformation. There can be no compromise. Mercy, compassion, loyalty: all these things will prevent you from claiming what is rightfully yours. Those who follow the dark side must cast aside these conceits. 503
Those who do not—those who try to walk the path of moderation—will fail, dragged down by their own weakness. Those who accept the power of the dark side must also accept the challenge of holding on to it(...)" <PERSON> avatar, to <PERSON> Wars: Darth Bane: Path of Destruction)
It was <PERSON> - who wanted to turn <PERSON> to the Dark Side - who told him that <PERSON> was a "good" man.
As a Sith phantom(linked to <PERSON>'s essence)- he goaded a female Jedi Knight named <PERSON> to kill him - and give in to the Dark Side - supposedly to make her his own Sith apprentice. He even assumed <PERSON>'s likeness, and she didn't give in. So he felt pitty for her and warned her to leave. And he never revealed the person who <PERSON> was linked to(which was <PERSON>).
Now - this power tells us something about <PERSON>. It needs a living host to summon a Sith phantasma - yet <PERSON> was okay with it. It's quite possible he experimented with his family.(Star Wars: Legacy of The Force: Betrayal)
<PERSON> continued <PERSON>'s lineage and eventually took an apprentice. It's possible his death was caused by his apprentice.
So - no. There is no good Sith.
<PERSON> tried to implement Jedi guidelines in the Sith philosophy and got mad enough to destroy much of <PERSON>'s lineage Sith lore; his end came when his apprentice - <PERSON> - stopped him.(Star Wars: Darth Plagueis) 605