I've been wondering this, too, and hoping that someone would answer your question!

I have some juices that seem not to wick well and to get a burned taste easily. I'm wondering if adding a drop or two of water will help? I guess I'm just going to try it, because if I can't vape them anyway due to dry hits, what do I have to lose?
With nothing left to do but try, I thinned mine with 1-2 drops/mil of vodka, and the difference was night and day...I've been through a tank and a half since the post, and no appreciable diminishing of my atty's output (which will get a cleaning tonite or tomorrow). So, 'try it' would be my recommendation, for now. In future, I will likely avoid this juice, but I have about 60 ml of it left and felt it would be a shame to toss away such a great flavor.
In general, I've noticed anything that imparts a sweeter taste (like "carmel" anything, and some of the sugary bakery flavors) tends to clog quicker. I think I'm gonna stick to the higher PG ratios, as they have have the qualities I want the most (wicking, flavor, throat), but I wouldn't mind checking out a 70/30 mix for more clouds, or even a 50/50 if I could find one where the flavor doesn't contribute so much to the clogging as I suspect some of these sweet flavors do.
I'd like to see manufacturers rate the color/transparency of their juice in the description, but I've yet to see that in any of the vendors I've gone with.
Oh, and another thing I've learned: When cleaning/dry burning an atty, there's a danger of consuming/burning your wicking material if you linger too long on the pulses or don't allow for long enough cool-down between pulses. This will quickly cash in your ability to wick...with the buildup I was getting on the cake batter flavor, I ended up killing an atty within a day or so of use by trying too hard to clean it, so watch that. Another possible solution would be a DIY rebuild with a looser wind on the resistance wire and/or looser wicking material, along with more frequent replacement....