Not even garbage necessarily, just a limited choice in lenses. The mirrorless lenses are being made by the same high quality established companies as the DSLR lenses, they just have fewer choices. To take MFT as an example, which is the biggest mirrorless lens mount by far, it has lenses by several different manufacturers but still doesn't have the same variety available of either the Canon or Nikon full-frame DSLR mounts. Here's the MFT lenses: http://www.four-thirds.org/en/microft/lens_chart.html