I am analyzing the Solomonic view whereby Spirits are seen as amoral, wild, chaotic and will give you your desire by any means necessary (even if it hurts you or your loved ones). They get you what you desire even if it hurts your loved ones or you…and the Solomonic view is to therefore be aware of their wild and sneaky haggling. If they haggle with you and try to change your plan/instruction for them ie, your desire…then how can they be your allies?
What do you make of that?
You have to remember the context in which the Solomonic grimoires were written. In the Judaic worldview, spirits are to be inherently distrusted. This is why fasting, prayer and purification are required before the magician summons anything. You must prove your worthiness to God and gain his authority before trying to control the chaotic nature of the spirits.
In the Solomonic system, the spirits are not your allies, they’re your servants. They serve God as does the magician.
My experiences inclines me to agree with Jason Miller. Spirits are very much like people just with much more power. So when they think they can take advantage of you, depending on their personality, they will attempt to negotiate the best deal for themselves at your expense. Not all spirits are like this though and they don’t have all the same wants or needs. Some will demand very little of you other than you try your best daily. Others will not provide in-depth assistance unless you fork over a kings ransom worth of physical, bodily, or symbolic offerings. They are not all the same and don’t all think as a hive mind. So it’s important to establish firm boundaries when dealing with them just as you would people. You have just as much sovereignty as a incarnated spirit yourself so don’t undersell yourself! 
I actually think if they f##k with you then it’s akin to a good sensai fuc##ng with you, it’s for your benefit. It’s a test so you step up, as you say they want someone who can establish firm boundaries., they don’t want a putz or a schmuck for an ally,
I’ve heard that said as a theory. It’s said that a spirit who never says no to you or gives you hard time if often a imposter posing as the real deal. I can say for certain as my spirit senses aren’t that great yet, but from what I’ve heard among those who’s are, there’s a great many frauds on the other side.