My lizard doesn't ever seem to smell apart from when he has just had a poo. as long as you dont leave it there for long and clean it up when you notice it, it should be fine. If the viv does seem to smell after a while just replace sand or whatever you use and give everything a good clean..
If the lizard does get covered in his own poo just give him a bath. I can only ever smell my lizard when he is directly below my nose. I personally think crickets have a horrible smell though!!!!