Most lizards can just hang off the wall to attain a better vantage point.
I built a lizard terrarium in high school. Smooth-walled, high density particle board on three sides, and a glass front. No way for them to get out. I dropped a couple of orb weavers in for food, and one of them climbed the wall in a hurry. Alligator Lizard walked right ip the wall and grabbed it.