Many breeders use sand for years and never have a problem. In fact I believe Kelli (Hisss.com) and Monte (Powergeckos.com) used to use sand for a number of years before switching to newspaper/papertowels.
I believe when your housing your reptile for display purposes or for your personal enjoyment, it should be stimulating for not only your pet but you as well. You should have their cage be most like their natural enviorment as possible, and strait plain slate or plain sand is far from what its like in the wild. I have made my own desert vivarium for Side-Blotched Lizards, a local desert lizard. The deserts, from what I hear, closly resemble those of the Leopard Geckos, a rocky/sandy outcrop with sparse vegitation. Here are some pictures.

This is the entire cage.

Heres a shot of the lizards and their basking area. I decided to use old narled wood, from the desert actually. I also used various sizes of rocks and mixed the smaller rocks into the sand/bed-a-beast mix so that there wasn't just fine sand, it more closely resembles the sand in the desert. I also used various sizes of bark, also from outside. The use of debri, narled wood, rocks, and bard makes the cage looked "weatherd". Another thing, right after I was done with the cage, there was a "thunderstorm" and I gave it a pretty good watering, however I will only do this maby every few months. This gave the subtrate a crust that allowed the lizards to dig their own burrows, and not that loose sand look.

Heres a top view of the cage. I used a rock with an impression in it and used that as a waterbowl, I my opinion it looks so much better then the rock water bowls they sell.

This is a shot of the cave that I made by simply burying a hide. I also used a piece of bark that is put across the cage and over the cave entrence and give it a sort of hidden look-its not just out there.
This kind of use of sand in my opinion is much better then the use of just plain sand or slate. It is much more stimulating for my lizards and I enjoy watching them explore their cage. It is much more pleasing to the eye because it looks as if I took a piece of the desert and put it in the cage.
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Bradley Baquial