Others have responded to your suggestion here and this is less to you directly, just on the topic since it's come up.
I see people reinforcing the fact that they are offering questionable bindings and that is definitely a concern based on what's been exposed, but a bigger 'tell' here to avoid persons like this are all of the red flags they have shown especially in recent years in their behaviors as well as what problems they have fostered in their community.
One of them was exposed for instances of animal neglect -- overall you shouldn't want to support someone who neglects animals, makes up excuses for it all the while offering furbaby protection rites or whathaveyou while this is going on. Think about that. It's just one example of several one should take issue with before even looking at the state of their conjurations.
Where there surfaces a question of whether or not someone's bindings are legit, those issues most evident are a direct reflection of the beliefs they subscribe to and their practice. I think this is overwhelmingly important to state.. people seem to care a lot about whether a binding is going to be real but I hope everyone here is going to care about what a seller is like as a person first and foremost, who you would be supporting if you provided them your business.
Of course, many who are seeking 'real demons' and are phrasing it that way, it is usually safe to presume don't care about the proposed ethics of a practitioner meeting reality -- since it insinuates you're just looking for evilly evil things.
The original poster hasn't replied at all so I'm not expecting to see them clarify what they have in mind when they say they are looking for 'real demons', but to be more explicit about intentions is what I think is needed before providing serious suggestions.
as trying to dismiss another user's experience in practitioners whom of which you don't know is not it
