Looking at the overall results - this is what I would say :
When I removed the head I cleaned it with the garden hose and a plastic brush.
Overall, hard to beat the vinegar. If you had to look at cost, ease of use, smell, etc, it would win in this particular go around. The Works (toilet bowl cleaner, not the other one) did really well, as did CLR, but both stink, need gloves, and cost more.
Mustard - jury is still out. It did ok. I think I needed to make sure you move it around, keep it moist(someone else pointed this out earlier or in another thread). I didnt keep it in a bag, so i made a cake like substance on the head, which i actually had to pry off. So I will say at this time, it needs another experiment.
Coca - Cola - ok at best. Not alot of action here. Pretty average to below average results. Not a lot of stuff in the bucket like the others.
Vinegar - This stuff did the job. All kinds of debris in the bucket when done. As you can see from the picks, just needs a good once over, and you would be good to go. I was pretty impressed by it.
The Works - serious stuff. But too stinky and too many things to prep and worry about for me. Same with CLR and Lime Away. Though I will say they did their jobs overall.
So that is the first experiment. I didnt cure a disease or invent a new kind of energy, but hopefully this can help, or we can continue to build on it.