AT&T's unlock policy is not open to customer service rep interpretation. Unlocking requires one of their conditions to met.
I don't believe anyone is getting random unlocks simply by calling a friendly customer service representative.
Here is their official policy statement:
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General Eligibility Requirements for Unlocking iPhone
AT&T will unlock an iPhone under the following circumstances:
The person requesting the unlock is: (i) a current AT&T customer; or (ii) a former AT&T customer who can provide the phone number or account number for the account.
The iPhone was designed for use on AT&T's network;
All contract obligations, including any term commitment, associated with the device to be unlocked have been fully satisfied; and
The iPhone has not been reported lost or stolen.
Current customers will be allowed five (5) unlocks per account, per year, so long as their account is in good standing with no past-due amount or unpaid balance and has been active for at least sixty (60) days.
Former customers will be allowed five (5) unlocks per former account so long as they owe AT&T no Early Termination Fee or other unpaid balance.
In addition, AT&T will unlock an iPhone for: (i) an active and deployed member of the military who is a current AT&T customer in good standing and is able to provide AT&T with deployment verification; and (ii) a person who purchased the iPhone from an authorized location at the "no commitment" price and can provide proof of purchase.
AT&T reserves the right to deny any unlock request that it concludes would result in an abuse of this policy or is part of an effort to defraud AT&T or its customers. AT&T further reserves the right to alter this unlocking policy at its discretion without advance notice.