These aren't the Slytherins that you read about in Harry Potter books - they aren't outright evil, just sort of passive-aggressively assholish. They're self-serving, but they make cursory attempts at decency and even charity. (Until it becomes inconvenient, then nahhh.) They're not particularly glamorous or cloak-and-dagger. They're like, the background Slytherins. The ones complaining "what's the deal with the talking paintings - shouldn't the dead stay dead?" at the dinner table and conniving ways to get an "A" in Divination by making minor things they predicted come true.
Not sold? Don't worry - we'll break it down for you.