Teeth Cleaning

Does anyone out there offer teeth cleaning as an extra service? What do you charge? Do clients sign a waiver, how do you make sure they know that there dogs will not go home with sparkling white teeth after one cleaning? What about dogs with bad teeth?
I'm considering offering this option, but i'm worried it will bring out more complaints that we would hope for.

I'm thinking of offering something like this too. Currently I sell the Petzlife Dental Gel and Spray in the salon. (I use it for my dogs and love it!) I was thinking of giving dogs a spray or using the gel with grooms as an add on service. I don't want to get into teeth brushing because it can be a little invasive, and can cause the gums to bleed. Not sure what to charge, maybe $2? Then hopefully I could sell them a bottle so they can keep it up at home. Win- Win.