I've seen many english speakers actively use さすが in a sarcastic manner to mock a great failure of somebody, but I believe it is improper usage.
Yes, it is improper.
Since the questioner seriously asked if さすが will be used in a sarcastic or mocking way that I haven't understand, I thought about it seriously by using situational examples.
Example 1:
Assuming the situation where Yamada who is a friend of ours made a failure written below, I'll try to verify whether the use of "さすが" is appropriate or not.
俺が、「無理だ」というのに、「どうしても」って山田が言うので、「それなら好きにしたら」って言ってやったよ。「結果は、見事に失敗。当然だよね。」
Though I said "Impossible!" Yamada told me that "I'll do it absolutely", so I said "Take your liking". "Yamada failed in his attempt exactly as I thought. I regarded this result as a matter of course."
Then I said:
A:(皮肉を込めて With sarcastic nuance)「流石に山田だ。」
B:(皮肉を込めて)「予想した通りでした。言わんこっちゃない。馬鹿丸出しだね。The result ended up with exactly what I thought. I cann't say anything. He's a fool, isn't he?」
At this time, I will consider if the above expressions can be used as natural Japanese.
A is unnatural in this context and it is impossible to give an ironical, mocking or sarcastic sense to this phrase.
B is natural, but "予想した通りでした" merely states that the fact is as expected, and there is not much irony or mockery in the words.
Example 2:
I have a friend close to the example of naruto's answer. He has no sense of direction.
When meeting at a karaoke bar in a downtown area, he usually comes late or calls up that he cannot get to the bar though he thinks he is in the vicinity of it.
Obviously we are sarcastically talking about his lack of a sense of direction while waiting at the karaoke bar for his arrival.
Even though, I do not know how to use "さすが" meaningfully with the sense of sarcastically mocking his behavior at such a time.
Conversely, I think that saying or using "さすが" with a sarcastic or mocking sense is not so natural in Japanese language.