"In North America I've been asked a single time in the 15 years I've been using Corp rates (for a few years I'd use them on multiple stays per week). My trick is to approach the counter in a friendly way, ask how they are doing, maybe ask an easy question about the hotel (where's the gym?) and connect with them (boy it's hot out there today!) They are happy to have met you, it is a pleasant experience, and you go on your merry way. I'm also Titanium for life and currently have Ambassador, but I've done this when Gold and Platinum. For that one time they asked I said I had actually just started and didn't have my business cards yet, but should have them for my next stay and they let it go. I was never asked by that hotel again (Courtyard Bellevue on an Accenture rate.) Doing a mobile check-in will also shorten the time spent. Just have your ID and card ready to speed things along."

"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."