Depends much on interpretation, mood, the reason for their summons, their general motivations, etc. "Evil" is a grey area. Many people will tell you that demons exist to manifest the negative emotions in folks, and many do delight and "feed" off of anger, cruelty, sadness, etc.
On the other hand, many "demons," were originally the deities and spirits of other religions, local cults, etc. The very word demon is derived from daemon, which refers to a spiritual entity that can be either helpful or harmful, depending on its personality.
As such, it depends very much on how you interact with these spirits, why they are there, and what their purpose is. Always be respectful. All magic calls for courtesy. Even when you are making demands of a spirit you bind to yourself. Always be prepared for a spirit/demon/angel to not have the same goals as you. And therefore you must always be prepared for the worst. Do not, however, invite it.
Let's say you are a Demon with all your wisdom and power. And there is a teenage boy with wicca toys and ritual ready to summon You. He want to take revenge on his enemies and make them suffer. He thinks he controll you, maybe he even can..and somewhere along the line everything collapse. How would you react than, would you hurt the boy or his enemies, or just walk away from human ignorance? Not all of them are same, they gather power on thousands of ways, many of them DO heart human...but not for nothing. But the main thing is that we are foolish if we think that we can handle some things so easy.
An indeed,if u respect them,they will respect u.however,if you are a demon that loves knowlege an woul like to share it,and a teenage boy summons u because he was bored,wouldnt you be kind of mad? I mean think about it for a minute! I know that would make me mad.