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.