It depends, are you checking in at the economy section or business/first class counter? At the business/first class counter they don't really care at all. They ask u to put ur carry on up and slap a little band on it and then tell you to take it back. If you are walking towards security from the economy checkin section, they have people there with scales and looking for these bands on your bag. If there is no band they ask to weigh your stuff (unless they miss you). What I have done in the past is just leave the band on my luggage so they wouldn't bother me

Normally now I checkin a the business section, so I don't get harassed anymore.