i won't let it get filmy and nasty, or to the point it's able to produce smells from 2 feet away. but i dont' clean it every time either. i either clean it ever coupe of days (that's if i'm not able to smoke everyday) or after a good 10 or so bowls. maybe less. just depends on if it's making the weed taste bad. also, when the ice in it melts and i desire to add more ice, i go ahead and dump it, rinse it and start off fresh.