They do leave a smell but it's nothing like smoke. It will clear in about 5 minutes with an open window or some Febreeze.

Although I've got to be honest with you and tell you that they're not worth it. I'm sure you're still going to make one but don't get your hopes up. It will take quite a bit of weed to get you high, the high won't be that great, and you may be disapointed.

If you can just go outside and smoke.