Nope. Not a bad idea at all. Actually, a great idea! Since they love plants then it doesnt make sense to put live ones in there as they eat them up in a matter of days. I had to learn this the hard way. I have three 4" dollars and they love their artificial plants.
One suggestion that I have learned from experience would be: don't get plants with sharp edges or prickly edges because the SD's scales come off very easily and you dont want to permanently scar them.
One last thing. Artificial plants are fine for dollars as long as you give them lettuce or other plants to eat regulary.
