You just gotta be aware of who you're dealing with. Look for the red flags. I recently posted a WTB for some tubes on a FB group. Someone messaged me that they had what I wanted. But I took a look at their FB profile and all the images were AI generated and they had zero real friends or FB posts/interactions that a normal, real person would have after being on social media for a decade or more.
I asked them for details on the tubes and instead of speaking like a normal non-lizard human, this is what they said:
"All are same matches set and new four for $300 shipped happy with the deals send information for a pro forma invoice and payment to proceed with delivery details needed Names Address Email Phone number Thanks main Stage Audio cheers"
If you still send money to someone after that... you might need your BS radar checked.