Perhaps the most famous of Goetic grimoires is the Lesser Key of Solomon, or the Lemegeton's Goetia. It's everywhere you look when it comes to conjuring demons, and most of my readers know I'm o exception. I use the spirits of the Lem's Goetia frequently, and with great success.
In a recent post to the Grimorium Verum yahoo group, a magician expressed her frustration with the grimoire, and questioned the spirit-friendly approach many modern traditionalists are adopting in their approach to these spirits. She had performed a conjuration of the same spirit three times and failed to get her desired results each time. She was questioning whether the spirits of this grimoire just sit around and do nothing if they aren't constrained by all the curses and threats of the Lem's Goetia, and any success that happened was mere coincidence.
This is pretty typical, in my experience. Magicians see that Bune bestows riches on a man, and do a Bune rite to win the lottery. They lose and torture the spirit's seal. I'm totally guilty of that myself, in my early operations. Never mind that I totally screwed up the rite, or that I was completely inexperienced in working with the spirit at all.
In my Modern Goetic Grimoire, I attempt to dispel some of the bullshit that surrounds this grimoire. Most of it is in the minds of the magician. Expectations run high, and the spirits "fail" a lot when you expect them to deliver something beyond their abilities. That's why over the years I have tried to tell people frequently that you need to conjure different spirits if you don't get the results you seek, or conjure them in a different way. Above all else, ask them why they aren't doing what you want, ask them to show you how to use them to accomplish your end result. Simply telling a spirit to make you rich isn't going to make you rich, unfortunately. Jason Miller addresses the relativity of the concept of "rich" in his Sorecerer's Secrets, and I think his insight is invaluable.
The chief failure of Goetic magic lies not in the system or the spirits of the system, but in the magicians themselves. They think that following the steps blindly will result in huge payoffs. They are only in it for what they want, not for what the system is designed to provide. Bad news, greed heads and lust-maddened sex fiends, the primary purpose of the Lesser Key is to provide you with knowledge. It's a pantheon of professors, highly skilled in providing you with the information obtained traditionally in a liberal arts degree from an institution of learning. They can do things on the side, like make people fall in love or get you rich, but the way they do it is seldom lines up with our expectations.
The first impulse is to question the system or the efficacy of the spirits. Some even question the efficacy of magic itself. To me this is like a person who builds a doghouse for the first time questioning the efficacy of their hammer if it turns out to look like shit. Magic is an art like many others, and requires dedication and experience to understand how to use it effectively. Conjuring the spirits is relatively easy, but understanding them and how they work takes time.
So if you're a new conjuring magician and you've tried to win the lotto and failed, or tried to sleep with the boss's daughter and failed, don't blame the spirits. It's your inexperience primarily that's causing the failures. Learn from the spirits, their primary role is to provide an education. Use them for this first, and the side benefits will roll in like the tides.