hehe.. Devil's advocate. I am sure Wulf suggested this tongue in cheek, because this would be insane.

Let me ask you forum member... when was the last time you checked to see if your top tube was perfectly level on a perfectly level surface plate? I would be very surprised if any of my top tube are perfectly level given all the variables that go into it.. tire variation, pressure, headset type. position of rear wheel in drop outs... small variations in the construction that are inconsequential... etc.