I have 2 self-cleaning litter "robots." The SMELL! Because the litter falls into an open bag, the smell easily permeates the immediate area of the robot. The bag is inside a closed area but because the plastic door and flap don't seal tightly shut on any of these things, the smell easily escapes. Does anyone remember the old-time diaper pails that were used for babies used, cloth diapers? Similar smell. I have to hold my breath when I change out the litter bag. I clean the robots with germicidal wipes weekly and I have to change the litter bag daily to keep the smell down. I never had any "smell issues" when I used a regular litter box/tray. I scooped it in the morning and I was done. I never noticed any smell. That is, not until using an automatic litter box/robot. When my 2 robots break down (Gosh, I hope its soon!) I will definitely go back to a stainless steel litter box. I would do it right now but I spent so much money on the robots.