OK, I just got my On Tap "Pale Ale" Liquid Beer Enhancer in the mail today and gave it a try. Basically it comes in a "Mio" style container. The ingredients are: Water, Propylene Glycol, Natural & Artificial Flavors, FD&C Yellow #6, FD&C Red #40, FD&C Blue #1. So my first guess that it used caramel coloring was off. Unfortunately, my second guess that it used hop extract appears to be off as well...
So I decided to give it a try just diluted in water to get an idea what it is. There is no specific dilution instructions on the package other then "Adjust to taste" and "always dilute in a glass of beer". The serving size on the "Nutrition facts" was listed as 2mL, so I used 1/4 tsp in 6oz of water to give the approximate concentration that would be added to a bottle can of beer. The resulting solution was maybe 4ish SRM, somewhere in the color range of a light apple juice.
Speaking of apple juice, the moment of truth was when I stuck my nose in the glass... and was hit with a distinct aroma of apple jolly ranchers. There was a hint of caramel in there as well, but that's it. Nothing remotely hoppy in the nose at all. I took a sip and it was slightly bitter followed by more of the apple jolly rancher flavor. It was slightly sweet, and pretty weak-flavored at the recommended dosage. There was also a touch of vegetal/herbal flavor, but it was almost medicinal and not pleasant at all.
So I proceeded to add the same amount to 6 ounces of PBR. It looks like it added maybe 1-2 SRM of color at most. The nose was more of the apple jolly rancher plus caramel, which overwhelmed the clean 2-row PBR aroma. The flavor was like you were drinking Pabst from an empty can of apple juice concentrate that wasn't rinsed out too well. In short, it ruined an otherwise OK beer.
So, needless to say I cannot endorse Ot Tap's product in the slightest, unless you are practicing for the BJCP test and need a stand-in for acetaldehyde. I have a funny feeling that's the major flavoring component in here. Makes me wonder if the "American Ale" version turns your beer into buttered popcorn. You will have to find that one out for yourself, as I will not be wasting yet another $8 bucks to test that one out.