There are a few reasons I can think of why it's still worth your time to do this. By knowing all the ingredients, you can assure that you're not disposing of dangerous chemicals into your trash. Re-using the bottle will also mean less trash to dispose of, and even if you recycle, it's still a waste of resources to make it usable again. All "Save the Earth" motives aside, it can be a fun little conversation piece with your friends. And finally, if you have pets or little tykes, I consider this to be a "less-dangerous" cleaner than what you may buy commercially. Knowing the four commonly available ingredients (three of which are consumable) could be resolved easier than trying to pronounce the five-syllable ingredients to a poison-control center employee. To be fair, I haven't tested the effects of drinking this concoction or that of the store bought variety.
This is my first instructable- just don't be an idiot because neither this website or myself are responsible.