There may very well be spirits of infirmity and deaf&dumb spirits causing sickness and disability; I accept that.
But I think that the religiously fashionable trend in trying to solve spiritual problems by identifying spirits is a convenient way of blaming demon spirits, when it is most probably a more simple and straight-forward case of hidden unconfessed sin that is quenching and grieving the Holy Spirit in the person.
It seems easier to get a person up in an altar call, cast out a demon spirit and everything will be okay, then to spend the time and effort in prayer and counselling to get rid of the unconfessed garbage in the person's life. Trying to cast out spirits as a way of solving spiritual problems is the lazy way and doesn't actually work when there are unresolved issues, restitution needed for wrongs done to others, and unconfessed jealousy, envy, and gossiping sins, as well as the more obvious sins that need confessing and getting right with God.
Most often, when a person has got rid of the garbage in his or her life, there is a new sense of freedom and release, and most probably not because they have been freed from some spirit or other, but realistically, the outcome of just cleaning the heart and spirit out of stuff that had been left to fester in the corners of the heart.