I always end up using my brand of scent in a couple of sittings, but I have read and wanted to pass it along, that if it smells like ammonia or a garlic type smell to shake it up real good then take the lid off and let it sit for a couple of hours. Supposeadly[sp?] that'll clear it up and it'll be good to go.
Don't know if it really works but if it does it'll save ya 10 or so bucks.
Good luck