Thank you for this information.Flagging someone is risky for the people like me as we don't know what that account actually represents. Flag wars are going on. Hence, even a user having a rep as low as -1 can be harmful if we don't know the big account associated with that small account!
And I have a doubt..If someone having huge SP and very low rep than me flags me,will it decrease my reputation?
People involved in flag wars aren't phishing accounts generally. as far as I know, a lower SP can't do much to a higher rep but, most likely someone with a lot of SP won't bother.