Bumping this thread again because after a relatively smooth & normal month of July, they seem to be back.
@diberry - yes, and this time I was on a run for the best week since Penguin hit, then BAM! all conversions stopped at the exact same number of sales as the prior few weeks. It "appears" like throttling by throwing Zombie traffic at the site. Weird! and frustrating!
Also, this time it's just US traffic, not seeing the usually high influx of foreign visitors.