While the word 'consensus' is commonly used in science, it isn't a great one.  Consensus means basically voting and the public does not want to think science is like the United Nations where everyone, no matter how right or wrong, gets to insure nothing ever gets accomplished because some remote dictatorship can cancel out the US.

So a vote on the existence of Dark Matter isn't legally binding but it is still sounds like fun.  

Michael Brooks (see my review of his new book Free Radicals here) attended a meeting of the Flamsteed Astronomical Society to debate the existence of dark matter 75 years after it was hypothesized. In a vote at the end, the audience decided it probably doesn’t exist.

"After 80 years," he writes, "someone’s found the handbrake on the dark matter juggernaut."

Not to sweat if Dark Matter is officially voted out of existence, like Pluto: If you really want to hold on to an anti-Copernican standard model of cosmology, there is always Dark Energy.

Does dark matter exist? by Michael Brooks, New Statesman