My car leaves black, sooty flecks on the garage floor on start up. It is only from one tailpipe which is weird, because I have a single pipe from the exhaust to the muffler, then dual tips exiting the muffler. The soot seems to only be coming from the left(driver's side) one... any thoughts?

Perhaps it is blowing out the other side too and I am just not finding it?

The driver's side pipe is an almost straight exit for the exhaust... More exhaust flows out of that side than the other because the gases are reflected and redirected to the other one. Go to where it's cold, if you're not there already, and you'll notice that the driver's side ALWAYS flows more than the pass side with a single inlet, dual outlet muffler like the Flowmaster 80 series.

My car spits the black liquid -sometimes- its fine.

It was a mystery to me, too, until i heard Chevys (old ones) like to do this.

I now know it is ok, lol.