Too sweet flavors

First of all let me say I really appreciate your help here on the forum! When I started diy I bought flavors of Pink Spot, Mom and Pop. You don't have to add anything but unflavored liquid. I like a lot of the flavors but some are just too sweet. I'm not such a sweet tooth and I was wondering how I could tone down the sweetness of these juices, without cutting down on the taste.

I thought of bitter wizzard but that's for tobacco's. I thought of Sour but wouldn't it become sweet and sour that way? Is adding vinegar a good idea?

Sorry for all the questions but it would be a waiste to buy something I wouldn't use.

 

Thank you blue moods. I'm a bit surprised I must say this topic isn't brought up more frequently cause sometimes these flavor concentrates are incredibly sweet.