Please see my response to your other post that shows the 8 warnings for SCP misconduct that you've received in 8 days. There are no specific guidelines for job blacklists, because they are at the discretion of JMT+ or Heads of Branches.
However, I use my own personal guidelines for when I decide to issue blacklists:
1) Multiple Incidents in a single job (Yes, as Dr. Bright)
2) Major misconduct on the high abuse trio of 106, 173, 343 (Not present)
3) Multiple misconducts on different SCP jobs (Obviously present)
4) Multiple misconducts in a short period (Obviously present)
5) Propensity misconduct will continue (Judgement based, and I judged it to be present)
You received numerous chances after being talked to and warned by staff, and failed to read and follow the MOTD. You were subsequently blacklisted to prevent further misconduct.