Garak was in all likelihood a spy and assassin working for the cardassians, that has absolutely no problem murdering someone if that's the easiest solution.
Quark is a ultracapitalist that would betray any value for money, is extremely misogynistic, does things like dealing weapons if I remember properly, and is fine with doing illegal porn holodeck programs of people without their consent. He is maybe less evil than he could have been, but on the scale he's definitely more on the evil side.
Obviously it all comes down to the definition of good or evil, which being undefined here makes things more blurry and up to interpretation.
