If you have a screen cage you can put a roach on the wall a little way from your Cham so it doesn't hide, and then they may notice it crawling. I do that with crickets if I don't have time for hand feeding.
I keep crickets and the smell isn't bad because I put wood chips in with them, and I clean out their cage at least once a week. I also keep their gutload in water bottle lids that I replace every day. If you do that they won't smell nearly as bad.
