This operational risk/misconfiguration was detected by a visiting SQL server consultant from Microsoft at my organisation recently. Just goes to show how you can achieve the VCDX and still know nothing.
Use Case: SQL Server 2012 running on Windows Server 2012 with vSphere 5.1 configured for 16 vCPU/128GB RAM on an ESXi host with 2 x 10 Core sockets and 512GB RAM.
vCPU Hot-plug is configured and since the VM has more than 8 vCPU, we ASSUMED that vNUMA was enabled and did not check it. WRONG! When CPU Hot-plug is enabled, vNUMA is disabled and reverts to Uniform Memory Access with interleaving. SQLPerformance also has a good write-up.
If you have large VMs with modern applications and operating systems that you ASSUME are using vNUMA, check them just to be sure.