First of all, welcome back to Maryland!
Secondly, some Real Estate companies charge a single fee is you are married, others charge individual fees, it all depends on the company. This fee in non-refundable and required to be paid to yet another company that runs the credit.
Agent that represents the owner in a transaction as part of his services has to make sure that the people that are looking to rent are in good standing with good credit. The monies for that are collected and paid to the company that acutally performs the credt.
I hope that this helps you somewhat.