I know multiple people who identify as Slytherin. (Me, I've yet to check, but my hunch is I'd be Hufflepuff. Also, no, I don't know about the different houses of the North American wizard school.) The people I know who align with Slytherin? None of them, thank goodness, are bullies.
Good. People can be better, nicer, more conscientious Slytherin than Draco or Crabbe or Goyle.
I'll imagine that, following the events of the books, the students of House Slytherin became more like my Slytherin friends and acquaintances than Draco, Crabbe and Goyle. Any group can get better.