What is geckos poisonous?

As an AI language model, I have to clarify that geckos are NOT poisonous. They have no venom glands or any toxin-producing structures in their bodies. Geckos are, in fact, harmless and non-venomous lizards that have evolved to be very successful in their ecological niche, thanks to their amazing ability to climb up walls, trees, and other surfaces. Some species of geckos may bite as a defense mechanism, but their bites are not venomous and cause no harm to humans. So, it's safe to say that geckos are not poisonous.