Mark,
To loop through all the the host one by one, you can try:
foreach ($VMHost in Get-VMHost) { Scan-Inventory -Entity $VMHost }
Robert
Blog: https://rvdnieuwendijk.com/ | Twitter: @rvdnieuwendijk | Author of: https://www.packtpub.com/virtualization-and-cloud/learning-powercli-second-edition