"hotelcorporatecodes.com specifically categorises the Bayer/MLM code as "Rarely" for ID checks — the only entry rated below "Sometimes" in the pharma-sector Marriott codes. The MLM ticker does not correspond to an obvious company name, limiting its public notoriety. Pharma codes as a category are generally Medium, but Bayer's specific code consistently surfaces in the "low scrutiny" tier on aggregator sites, consistent with a large but relatively travel-light pharma footprint compared to consulting or finance."

"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."

"I also use AAA if the corporate is not available. In 10+ years of using AAA I had never been asked to show the card until last month in FL at two different properties. One was a HGI in Palm Beach Gardens and the other a CY in Stuart. Stayed at both since on AAA rate and wasn't asked."