I've received some invitations to be a referee in my email recently. "Hey, we're starting a new on-line journal, if you want to submit articles or be a referee for us... If you want to be a referee, send us your cv."
My reaction, always, is to delete the message. Why? I have enough peer-reviewing to do already. I can publish, myself, in better journals. Being a member of an editorial board or being asked to referee a certain article in my speciality is fine, but I don't need to send you my cv to referee for you! I am an established, senior scholar in my field at an R1 institution and if you are contacting me at all to do peer reviews you should know who I am.*
The journal in question who most recently contacted me requires that their referees simply have a PhD and be college faculty. (Any idiot can get a PhD.) There is no effort to get the most qualified referees, merely a mass email sent, I presume, to many, many people. This particular journal did not seem to be scam or one that required a submission fee. That is all the more unfortunate. If someone is starting a legit journal, they should contact distinguished scholars for the editorial board, not a random group of no-name referees.
*"Do you know who I am?" is always an assholic thing to say. I apologize for sounding like an asshole in this post. Even if you feel the urge to say that, don't say it. Ever, Even if the person who's irritated you deserves this response, you will still be more of an asshole than that person, who is simply dumb, rude, or ignorant, but is not the arrogant jerk that you are.