Running bad is simply being in a prolonged period of having results that are way worse then what they should be. If you usually win say 1/2 BB per hour, running bad would probably be something like losing at a rate of maybe 1/2 BB per hour for like 2 months (that would be running REALLY bad IMO). Usually people only refer to running bad when they are losing but then again if you go like 7or8 months of breaking even and you should be a BB per hour winner then this too would be considered running bad.