the #1 clue for me is when they call you, and yet don't seem to know EXACTLY who you are. I've gotten calls about my computer where they didn't seem to know what operating system I have. There are the calls where they don't know which credit card I have. I got a call one supposedly from my "bank" ( I use a credit union) where they said that EITHER my savings or checking had been "hacked". "Which one"?" They weren't sure. Well, I wasn't gonna know either. When my credit card company calls me because of suspicious activities, they spend alot of time telling ME alot about what concerns them. They tell ME the last 4 digits of the specific card they are calling about. Yes, somewhere along the line they ask me to confirm who I am, but usually with some piece of info that is relatively publicly available like my zip code or something. And quite honestly, I usually get immediately on the Web and go to their page and log in and find all the same info they asked me about. These days, I'm often getting texts from them about the same time the phone is ringing, and my email is tagged as well.

I really don't accept any calls from unknown numbers and spam emails simply get deleted.