If someone Successfully received a TS SCI in the military. got out but the clearance was still good. Then smoked pot. Then took a poly for a civi company, would that information be bad? This person admitted to experimenting with pot before the initial clearance. but would telling the poly-examiner this about smoking again after the military prohibit passing the poly? This person has not smoked it in the last 3 months.
Your question has more to do with security clearance adjudication criteria than polygraphy. Any use of any illegal drug after having received a security clearance is considered highly derogatory and is likely to result in a denial/revocation of clearance.