There is no Holy Grail. Every trick has weaknesses. If you cannot tell the weakness from a trailer, stay away from it. The reasons for not seeing it is either that crucial parts have been cut or that you are not experienced enough yet to see the weakness. If you are reading this blog the first one probably applies to you. If you see the weakness, then you have to decide if it is something you can live with.
Example: Volant by Alan Rorrison
If you played around with the gimmicks involved, you know that you need that exact necklace and that it might not suit your style. And that the necklace cannot be examined. Not even parts of it. If you are confident enough to be able to deal with that and if the necklace suits your style, then by all means get the gimmicks and the handling tips by Alan.
However if you have no fucking clue how it is done then one of the two points above apply to you. Actually the second point.
And that leads to the logical outcome. If you cannot tell the method from the trailer, you should never buy it. Basically the exact opposite of what is the norm nowadays. Magicians buy the stuff they cannot figure out. You should never do that!
Because the actual method's weakness may not be manageable by you or, you are simply not experienced enough to handle it.
Here is another example: Smokin Flash Silk by G Sparks
I really don't know how this works, nor do I care. But I know that I am probably not able to do the trick justice. If even the man himself cannot do anything but a cringe worthy demonstration.
And as a general rule. Stay away from cards! You do not need more card tricks!