There are forums in which I have seen that do provide some explanation of how magic or magick if you will works. I have seen a general overview of what is commonly referred to as 'The Basics' posted within the General Information section of the forums that can supply a general idea of what is reality and fictitious.
Though, since this is a forum in regards to spells and which are real and which are fake I will attempt to shed some light to discern which is which.
We all have a general distinction of what can happen and what cannot happen: for example, we cannot fly like a bird for our genetic make up does not allow that and gravity prevents us from 'floating away'. Therefore, a spell to try to grant you the ability to fly like an eagle will not work. Man has made planes for this purpose.
In some shows, like Harry Potter or games like Skyrim it shows magic to supposedly transcend all your human limitations: shooting lightning bolts and fireballs for example is beyond our capabilities. We could not physically sustain the amount of energy that it takes to produce such forces. Lightning usually kills those which it strikes, it can nearly reduce a human being to cinders, same with fire, which actually can reduce an individual to ash. We cannot handle the immense temperatures that a fire can get up to, otherwise people wouldn't burn to death if they were lit on fire. Therefore it is impossible to preform a spell that supposedly grants the ability to shoot fire balls like the Human Torch.
Now to provide some examples of a spell which works; let us take a ritual for healing and how it is possible to be done. Though it is not an instantaneous progress, it gradually happens. Let us use the common cold for example. We go about healing using visualization, meditation, willpower and intent. We visualize the cold as a type of sludgy, sickly energy within the system. A method I personally use is envisioning a golden light of warmth and positivity enveloping my body pushing the putrid energy of the cold out and down into the earth. I would repeat this and at first it may appear as if there is not progress, but over a course of two to five days of repeating the notion you eventually feel a lot better.
Ultimately, if you see the results of what you are putting forth and what spell you have done come to pass, then would you not say it worked? Though, there are many which claim they have achieved the impossible through magic yet none of them can truly prove what they have said to be. So honestly, personal experience is what we have in regards to a spell working. However, just because one says it works, does not mean it has.
In conclusion to depict a fake or real spell is using your common sense and intelligence. There are limitations in what magic can do. It is not as limited as our own mind, but limited by the possibilities we are limited too.
Hopefully this sheds light on identifying reality and fantasy.