Users that are supposed to have a colored username in the tab list don't have one. If you take a look at the users "masterchief0707" and "jerkboy2006" you can see that in one picture they have their respective green nametags in the tab list, and in the other their names are the default white color.
Environment
64-Bit operating system, Windows 7 version 6.1, Java 1.7.0_65
Previously reported in MC-73027, closed because unable to reproduce. Can you reproduce this on a 1.8.1-pre1 server and client?