i don't know as there's anything particularly sneaky. As ENki pointed out, generally arbitaguers are doing the market a service.
Also, iirc, @complexring and @jl777 both posted pretty detailed articles on how to take advantage of the arbitrage (at the time, it was in the other direction)
I see. As I said I'm not a Stockmarket trader, all this is new to me... So much to learn, and I'm learning more everyday. Thanks!