I once heard an argument on a skeptical podcast: Why do we never see any Bigfoot roadkill?

That's easy. Bigfoot must be stronger and more durable than cars. The real question is why we don't find Bigfoot faeces with traces of partially digested steel, oil and rubber from Bigfoot's vehicular combat success.

Let me expand: I assume Wikipedia would link or discuss the best evidence for Bigfoot. It does link evidence, and the quality of that evidence is poor. As of this writing, the most recent evidence listed in wikipedia is a 2007 photo that forest rangers assert is a bear with mange and a 2008 youtube video link to what pro-Bigfoot groups apparently admit is a hoax.

None of this is higher quality evidence than the famous 1967 film.

Imagine a ten minute encounter with a para-normal / unexplained phenomena. In 1967 or 1980, it is essentially luck whether the observer has decent quality recording equipment and time to get into position to make a good recording. In 2013, the smartphone-per-person density is such that we should expect the vast majority of sighting of Bigfoot, or UFOs, or whatever, to be recorded by smartphone video cameras.

90% or more of those recordings will be crap, but the sheer volume of possible recordings implies that we should expect to see some very high quality evidence by now. And we haven't (more precisely, wikipedia has no such link, which I think is equivalent in these circumstances).

Further, this analysis ignores the fairly large number of people actively searching for para-normal / unexplained phenomena.