That's right, the color of the smoke gives you some idea as to what the cause of the smoke is. This has also happened to me. Sometimes when I downshift then go WOT, I noticed a puff of smoke. It seems to be black, but I couldn't tell for sure. This doesn't happen when I accelerate normally though. I'm hoping that it's from running too rich because I still haven't done a compression check. If it's a puff of blue smoke, then your pistons might be going or your head gasket.