Most people will not want to consume carbs on off days, even on Density Bulk. The only people that will want to consume carbs on off days are people that aren't really concerned about staying lean (performance focused or completely dedicated to muscle gaining) or people that are just really big, like a lean 220+ lbs.This is assuming you are doing CBL in the traditional manner where you aren't counting calories or macros. If you are doing CBL IIFYM style, then you can consume carbs on off days if you want because your caloric intake is controlled.