I had one of these years ago I had given away and then recently bought another one.  Initially, it was a big mess as some other reviewers have experienced - the litter would stick to the bottom, get stuck in the rake, just make a gunky mess and nothing would help - I used silicone spray, cooking spray, took the rake off, etc.  I knew I didn't have these same problems with the Litter Maid before and *finally* I figured out I was using the wrong litter.  I was using Fresh Step clumping, which I used in my other boxes, but after reading other reviewers recommendations I switched.  Now I use Tidy Cat Scoopable for multiple cats (Walm@rt) and it works fantastic.  With one cat, I dump the waste 2x a week - it's takes less than a minute.  A different litter has made a *huge* difference - even the clumps in the receptacle dump out easily, very little left sticking to the inside vs. the other litter.  I know Litter Maid also sells their own brand, but I you don't need to spend the extra $.  Spray the interior of the box and the rake with cooking spray, then put your Tidy Cat in and do not overfill.