I've never seen an astroturf that I would be inclined to use as a substrate for leopard geckos. It's generally made from plastic, thin but not soft, with corners at the edge of each piece which are pretty sharp. I can't stand walking on the stuff barefoot because it's uncomfortably pointed and my skin is a lot thicker than that of a gecko.
Plus it'd be hell to clean. Feces in-between those horrible little plastic blades, pushed into the weave underneath. Euuughck.