4. Still talking to their exes. Depending on context flag color changes.
5. Smoking. If its done considerately, that its only a yellow flag. Done inconsiderately then its a red one.
6. If they’ll cancel plans with you because another friend wants to hang out. Once could be a special occasion or a close friend they haven’t seen in a while. Twice means they aren’t respecting you or your time (dealbreaker) and/or aren’t comfortable with you meeting their friends (for any number of reasons that are, in and of themselves, likely dealbreakers).