Head over to CCM and click on a host. Disable it. Now head to a hostgroup and add hosts to it. The disabled host shows up as "Inactive object" on the left side of the host list but as soon as it's added to a hostgroup, the information icon goes away and there's no way to tell that it's disabled. I assume the same thing happens to services, but I didn't check.
All of us on the call agreed that it's confusing. Because if you have a host in a hostgroup, then disable the host, then later go look at that hostgroup, you'll have no visual indication that any of the hosts are disabled, unless you first remove them from the hostgroup.
We think there is room for improvement here by making the right-hand-side appear the same as the left-hand-side if a host is disabled.
Thanks!