QoS trust cos vs trust dscp?

Just want to see what you guys think regarding qos marking for using the trust cos and trust dscp, say only on Cisco platforms.

My thought process is below, assuming the inbound traffic does have either COS or DSCP value set:

• If traffic inbound on the switch access port connecting to phone, I generally do trust cos and also configure global cos-dscp mapping. I think switches are actually using DSCP value for forwarding traffic.
• If traffic inbound on the switch trunk OR access port connecting to a switch, I generally do trust cos value.
• If traffic inbound on the switch trunk OR L3 port connecting to a L3 device, I generally do trust dscp value.
• If traffic inbound on the router interface or sub interface connecting to a switch, I generally do trust dscp value.
• If traffic inbound on switch/router port connecting to a computer (server, laptop etc.), I generally have to do manual marking...

What do you normally do?