Silently dropping QoS marked packets on the greater Internet

I've recently run into a hard-to-troubleshoot issue where, somewhere out in the greater Internet, someone was silently dropping packets from my company that happened to be marked with DSCP AF21. I'd fully expect others to either ignore these markings or zero them out but just silently dropping them seems unnecessary. So, how do you guys treat marked packets that come into/through your networks?