Can slytherin be good

Answer 1

No, that's a common misconception. If you are sorted into Slytherin, that just means that you will do anything to get what you want, which I do not see as a bad thing, although, if you take it too far, people may be hurt by your actions. But people can also be hurt by your friendliness, cleverness, and bravery, you see.

Well, not every Slytherins are evil, arrogant or cowardly, neither are every evil, arrogant or cowardly people Slytherins; only there is a strong correlation between the two.

The house isn't evil but the founder and several of its students were. Being in Slytherin does not make you evil, that isn't one of the house traits. Not all bad people are in Slytherin. Many people believe all Slytherins are evil simply because the only Slytherins we meet in any great detail are. However, we know of at least one who isn't evil: Andromeda (Black) Tonks didn't follow her family beliefs and was blasted off the tree. She then ended up helping the Order of the Phoenix.

Answer 2

Not necessarily. The key elements of Slytherin are being proud of your heritage and being driven to get to your goals. But being proud of their pure magical bloodlines, people in Slytherin are more inclined to be biased against muggleborns and halfbloods. As such, they were more ready than the other houses to join Voldemort.

Proof that not all people from Slytherin are evil: Horace Slughorn (who is somewhat selfish, but ultimately not bad), Arcturus Black and Severus Snape (who were both followers of Voldemort who ultimately betrayed him and were instrumental to Voldemort's downfall).

Proof that not all bad people come from Slytherin: Peter Pettigrew (heaven knows how that coward got into Gryffindor).