PayPal safe?

Another concern.
Did you know that a Bank Certified check can be cancelled?
My buddy is a banker. I asked his advice when I sold my Race Car in 1995.
The guy was going to bring a Certified check & I insisted on cash or no deal.
He was coming from California to Oklahoma.
Looking back, I guess the cash could have been conterfiet.
Now that I know the guy, we stay in touch & talk at least once a year, I should have taken a personal check from him. Oh well, you just never know.