Firstly, the following definition is anything but accurate:
March 26, 2007 Urban Word of the Day
A witty mannerism, personality, or behavior that is a combination of sarcasm and cynicism. Usually accepted as a complimentary term. Snark is sometimes mistaken for a snotty or arrogant attitude.
Her snarky remarks had half the room on the floor laughing and the other half ready to walk out. "
This definition is ironically highly endemic of snarkiness. Only a snark would say that being a snark is a good thing at all.
In fact its quite obvious that someone who behaves in a snarky manner and views their own behavior self-righteously wrote this.
By definition "snarky" is derogatory.
It means to not give the "principle of charity" (google that) to things others say which you disagree with, and in fact specifically withhold it as much as is humanly possible. It means to make straw men out of everything said you disagree with, and then pompously ridiculing the strawman you've errected in place of what was actually said, but acting like it was the actual thing said when your dishonest tactics are addressed. It means, not only being sarcastic, but being self righteous, condescending, and pompous. It means not accurately seeing things, and instead having them skewed by your desires, your ego, etc.
The above refuted definition is actually a perfect example of being snarky.