You may have been fooled in the past, but you won't get fooled again. You're wise to the ways of the world.
If something seems fishy, you stay far away from it. And if you're not sure, you investigate.
You know how to protect yourself. You know how to cut through the crap and see what someone's truly about.
You may come off as skeptical and doubting, but you've found that your skepticism is often warranted.