hmmmmmmm.......not to be rude or anything but i think your grandma smoked too much. i was reading that thc dissapates in the air after about 45 min or so. thats why you can hot box in a room, and the next day, it wont smell like it at all. imagine if you hot boxed a room with tobacco smoke, the smell would stay around for like a month. i dont know why anyone would think that you would have to repaint the walls if you smoked in a room. if anything, resin would build up on the walls before you had to paint them. she is full of it.