The last energy "shot" I used was the ABB brand. I think many companies offer comparable ones now - no sugar, but lots of (probably underdosed or useless) other ingredients. The caffeine is primarily what matters, and is what you actually feel working.
Speaking of "feeling," some manufacturers have taken to adding beta alanine to their formula, which provides a niacin-like tingle. People, for the most part, are fairly simple creatures who desire instant results. While it takes months to see the results of the protein supplements you consume to help build muscle, the effects of pre-workout products are noticed immediately.
Even a simple caffeine rush is adequate to satisfy many people enough that they will continue using a product. Add some tingly skin, and now it's Harry Potter-type shit!
Shots are convenient. Many cost less than a cup of good coffee. About the only benefit you'll get from them is the caffeine push. If that's all you need, then you're good to go.
I agree! It's definitely the "rush" I get in the beginning stage of the workout that causes me to continue using caffeine products like these. So I think it all gets down to caffeine content. I simply think these shots are much more convenient than other forms. Sure, you could take a pill but that seems so boring to me. Thanks for the thoughts!
On a side note, I've tried the Stackers. They work great too, but the taste was very hard to get over. I personally found the Eternal energy ones to be much better, hence why I recommended them (they have a few more ingredients as well, could be for placebo effect though). I think I picked up em up for around 86 cents each