Does the Petri dish lid orientation on workbench affect aseptic technique?
DISCLAIMER: I am a computational biologist and haven't touched a Petri dish since I was an undergraduate biology student.

I would expect that the best thing to do would be to place the lid face down. 
When placed so on the bench, it is only the tip of the lid that comes into contact with your (presumably sterile-ish) bench. If you place it face up, the interior of the lid will come into contact with the air of the lab. Despite the presence of the bunsen, I would expect that to gather more contamination. 

Since the lid is larger than the dish itself, the lip of the lid never touches the dish. Therefore, if the lip of the lid touches the bench and becomes contaminated that is not a big problem since that contamination should be blocked from spreading to the actual culture. If, on the other hand, the lid were placed face up, the interior of the lid (which hangs just above your culture when closed) will have come into contact with possibly contaminated air and could then cause contaminants to drop onto your culture.