My yard is just inches above the bordering river, doesn't help with the moisture issue.   If the cord was laying on a dry desert like surface?

Granted, any leakage current would be very small..   current none the less..
Then again,  I've picked up an extension cord left laying out after a heavy rain and found that the female end (in a puddle) was warm to the touch.... (lots of night crawlers dancing on the near by grass)  (yes I had on rubber boots)