I name machines using the name of the town they come from. A few sampes:
-Chippawa (Chippawa Falls)
-Cloud (St Cloud)
-Blaine (Blaine)
-Rose (Roseville)
-Shore (Shoreview)
-Ulm (New Ulm)
etc
I find it fun doing it that way, every name brings back memories of the previous owner. I remember interesting things the owners told me when I picked up the sewing machine.

I don't usually give them names either. However the ones that need work, stink and are beat up are referred to as the Derelicts..... Every so often one of the derelicts call out to be put to work one way or another.

As some of you have said, sometimes you call them names that can't be printed here -- If I get disgusted because of a machine foul-up (even if it's my fault) I have this saying I use, "Everything in here starts with a "J" for "Junk" so if I have a foul-up with a machine, I'll cal it a piece of junk -- that's the only name I've called them!
Jeanette