Spiritual Etiquette?

I’ve been seeing a lot of discussion elsewhere about approaching new spirits and what is the “appropriate” way to do it. One of the arguments for approaching spirits in an “appropriate” way (however that is defined with respect to the spirit) is that it prevents you from being duped by malevolent spirits masquerading as the intended subject which led me to wonder.

How do you and/or your practice view malevolent spirits? Do you believe in malevolent spirits? Are they a common danger? How do you make sure you’re ACTUALLY talking to the spirit you intended to reach?