UGH! NO!
I thought THOSE days were gone! But I guess it was just my change in environment, because this is a conversation that I over heard yesterday! Names will be changed to protect the...well, guilty.

Loan Officer #1. "I just had another lender under cut my rate"
Loan Officer #2. "What did you quote?"
LO#1 "4.875%, but I'm not even sure I could get that! Someone else quoted him 4.5%!"
LO#2 "What are you going to do?"
LO#1 "Send him a new Good Faith Estimate at 4.5%"
AAAARRRRRGGGGHHHH!!!! WHAT???? That's your answer? To send him something even more bogus then the bogus quote you already sent to compete with someone else's bogus quote!
Look, I dont have to call leads anymore and I am thankful every day to be running a referral based business. I understand feeling like you need to compete in order to get loans closed and that the person you are competing with is straight up lying. But, that does NOT give you the right to mislead a client! EVER! Do your best to win that client and if all else fails, walk away with ZERO commission and your integrity intact...its worth more.

And I say this to ANYONE buying a home that gets faced with this kind of situation...if you feel that your lender has unjustly changed the original terms to your loan...DONT CLOSE IT! These kind of bait and switch, harm and flip, tactics continue to get used because they continue to work.
A shady lender knows that there is a LOT on the line when it comes time to close. If you start to change your mind you will get pressured by Realtors, pressured by spouses, pressured by your current landlord wanting you to vacate or by the person buying your current home. You are likely to cave to the pressure and close anyway. That's why LO#1 doesnt think twice about quoting you 4.5% and then closing you at 5.5%.
Thanks for the advice.