Welcome!
There’s a few things I’d recommend if buying:
1. Make sure the photo’s are good and show edge condition and everything is clear (if the seller isn’t willing to put 5 mins effort in taking pics, could be an amber flag). Chip counts should match the pic.
2. Most folk sign their PCF handle on a postit with the date to give some more confidence they aren’t re-using another for sale pic.
3. Most folk selling have been on for a while, so can be somewhat more comfortable - you can search and see if they’ve sold before
4. If it’s a brand new member with no history I’d ask more questions.
Overall I think it’s pretty safe, but there have been issues in the minority I think.
GL