Suffocation only happens when you introduce too much Co2 too quickly and the carbon dioxide doesn't have a chance to "trickle" into the lungs, replacing the oxygen and causing SLEEP. Signs of a "bad kill" (or no patience on the users end) are choking and very deep, laboured breathing. Those of you who have witnessed these symptoms before, have witnessed a "bad kill". This type of behavior is not indicitive of the responsible herper.