Lol, I do this. My customers would often try to run my software on dusty old servers and then complain that it's slow, so now I just send them the hardware for free.
Different team, we did a cluster install and they were getting 10% of our advertised transaction rate. Something was clearly off. I commented “did they plug the whole thing into a 10Mb hub?”
They had. We sent someone eight timezones away to find that out.