"I have never been asked (yet) at Marriott but usually I show up at the desk by handing over ID/credit card. Don't read this as me endorsing going crazy using the codes that you aren't supposed to use! Interesting about the client reports going back daily."

"Deutsche Bahn's Marriott code 11353 is a German railway operator code in the global GDS system. Outside Germany, this code is essentially unknown to hotel front desk staff. German Marriott properties near Deutsche Bahn offices may be more familiar, but the code is rarely discussed in English-language travel forums. No verification incidents found. European public transit company codes attract minimal scrutiny."

"It’s about 80/20 for me. 80% of the time I still have to go to the front desk. I’ve asked the front desk folks, and they always say “our property has a policy to not allow mobile check-in”… I guess Marriott allows this at the property’s discretion. One property said they don’t want the guest to get stuck with full charges if they end up having travel issues and mobile checked-in the day before."