Regarding lifetime status, one time a check-in agent at a Renaissance told me that it was my anniversary of joining Marriott Rewards (giving me a free drink chit in the process) and I asked him how he knew - he showed me his screen and it showed my join date, points balance, lifetime to date nights, last stay, and other information. So if someone saw a Platinum with 750+ nights (I think I was at around 730 at the time), right or wrong they might hazard a guess that the person was lifetime if they happened to check that piece of information.

So at least based on what that agent showed me, at check-in they could at least discriminate based on life to date nights, points balance, join date, etc...