what are the effectiveness of probiotics?

Please can you tell me what the evidence is that probiotics are effective in the treatment of bad breath?
I have recently purchased some from Breezecare (fresh breath clinic in Australia/ukclinic) which is a mouthwash and gargle. I have no idea if they work but I must say they don't leave a very nice taste in my mouth. I then made some enquiries at another clinic called something like centre for breath treatment in San Francisco to see how their products differ from Breezecare and they say that they don't sell probiotics as there is no evidence that they work. I'm wondering a) about anyone's experience of probiotics and which ones advertised on your site had worked for them and b)what scientific evidence there is that they do work

Finally thank you so much for this invaluable website