I found that WinRM requires TrustedHosts (in WSMan:\client) to be set to run remote PowerShell commands. I am unable to find official documentation on the security ramifications and risks of trusting dangerous hosts.
In my situation I have a shared RDP server connected to a domain. I would like to give users access to connect remote PowerShell to potentially compromised systems, which are not on the same DC.
Client side TrustedHosts allows you to connect to remote machines whose identities can't be verified either through domain membership or SSL certification. Since it's impossible to know if the endpoint is friendly or hostile, the security model requires you to vouch for it by taking an explicit step.
Your question wasn't clear about running commands remotely, so I'll touch on a few topics.
This has little to do with whether you can run scripts hosted on a remote share - that's execution policy.
Likewise, with a knowable host via domain or https you don't need to set the TrustedHosts to run commands in a remote context.
TrustedHosts is just about making the connection in the first place.
Think very hard about your stated goal that you want to allow remote connections into compromised systems. You start opening yourself to pass impersonation attacks. If you know a system is compromised, you should be very wary.
Additional info:
Managing Non-Domain Computers
When you make a connection, by default, remoting delegates your logon credentials to the remote computer. The remote computer uses those credentials to impersonate you, executing the commands on your behalf. As you can imagine, there are security risks involved when delegating your credentials to a remote server. For instance, if a malicious user was able to successfully impersonate a known remote computer, you could possibly turn in your credentials to that impostor, who could use them against you and other people in the network http://resources.intenseschool.com/remote-management-with-powershell-part-2/
