Cleaning coins should be regarded as taboo. I find it hard to believe that cleaning is "Not harmful" to your coins. Years from now, even those "safe" cleaners will be found to cause harm. It happened to the "safe" cleaners of the past. (I kind of see it as- eggs and cholesterol - one year eggs are good for you and have minimal impact to cholesteral levels, the next year, the opposite) - IAs for me, I would never clean anything. But if you want your coins shiny, keep it to the culls and other low value coins.
I guess it would depend on just how far you are willing to take that statemet: As for me, I don't use any of those liquids on my coins. If they don't clean up with a good old wire brush, I leave them dirty. Just kidding!
If I am supposed to use Zippo Lighter Fluid on my coins, do I put coin cleaner in my Zippo? In any case, I have been dipping and otherwise messing with some coins (circulation ones, euros) in the process of an ongoing defacement (counterstamping) project, and it is interesting to see some of the effects. Needless to say, they are quite unpredictable, and I would not want to try anything remotely like this on a collector coin, so that includes suppoosedly harmless explosive liquids. There is something in lighter fluid that burns, and it ain't distilled water. On further thougt, I suppose that good old rubbing alcohol also burns but dries fast and cleanly (?), but I think lighter fluid is petroleum based (I could be wrong), whereas rubbing alcohol is, well, alcohol based.
Rubbing alcohol, like you get at the druggist, is about 20% - 25% alcohol and the rest is water. Best for cleaning is regent grade alcohol, usually 99% or better pure. This can easily be obtained at a chemical supply place, though you might need to show ID to purchase. BTW, Isopropyl alcohol (rubbing alcohol) is petroleum based.