This is exactly what i am talking about. Low intensity half assed cardio on days off, lol. Just something to get your heart going on days you don't work out. It is called active recovery. A few years ago i was doing a very physical job and was walking around doing labor all day and went to workout right when i was done and i made some pretty damn good gains AND stayed lean. Maybe i am a freak, who knows but cardio helps IMO. I used to be one that said no cardio at all, its gonna burn precious calories and make you lose muscle but after some thinking over the years i am leaning the other way.
My job isn't very physical and my body would love to be 175 pounds and skinny-fat. The low intensity cardio (3.5 mph and 8-12 degree incline) helps me stay reasonably lean while bulking. I'm squatting every workout so it helps flush the toxins from my lower body too.