If create operation fails detectable way (i.e. not during VM installation) 
there should  be no incomplete VM directory left, unless explicitely requested.

I.e. there should be option of create command (--debug or alike) which prevents it from cleaning up after unsuccessful creation. 

If this option is not specified, and VM creation fails after directory is created, directory and all files in it should be deleted.

No --debug option yet. But really there is nothing to debug.