Host Profiles is a really useful new feature of vCenter. However in some situations they could be more intelligent. For example when you define in the host profile to add an additional nic to vswitch0 to make the management network redundant, this results in deleting vswitch0 en recreating vswitch0 when you apply the host profile.
During the execution of this tasks the configurations ends with a communication error between vCenter and the ESX host because the management network is not available anymore (due to deleting vswitch0).
Also when a host profile with a configuration that enables VMotion on a selected vmknic is applied to an ESX host, the selected vmknic might not get enabled for VMotion on the ESX host. If the ESX host is checked for host profile compliance, the compliance status might be displayed as Non-compliant.
More information in the following VMware KB:
vKnowledge 