Nope, never been scammed. I used to be a freelance artist. I drafted up an art agreement contract stating my rights as the artist and their rights as the commissioner. Their legal name was required, along with their preferred name if applicable, as well as an e-mail they could be contacted by. If they refused, then I simply wouldn't work with them.
This protected me from exploitative or verbally abusive behaviours, because I included that if they behaved inappropriately towards me that I had the right to cancel their order with no refund or only a small percentage of what they already paid. I avoided most issues thanks to this.
And yes, I did require payment up front, though what I typically did was require a downpayment (a percentage of the total cost up front), and then work up to that point. After reaching that point, they'd have to pay me the rest for me to finish the piece and send them their files. Oh, and every screenshot I gave them, I spammed watermarks all over it.
I've only ever had one person who never continued with their commission but I still got paid for the first half of it.
The closest I was ever "scammed" was when one of clients apparently ruffled her ex partner's feathers somehow, and he tried threatening me and demanding that I needed to tell him how much she spent on commissions lest he drag my reputation through the mud. (Since this is very vague, I can say she paid nothing. She was one of my pro bono clients.) But per my contract, I couldn't relinquish any private info about any of my clients and their commissions unless it was required by court order. I went to explain this to him, but he ended up using a burner e-mail so I could never tell him.
So, be careful about instances like that, too, when someone tries to coerce information about a client of yours. The only thing that will actually hurt your reputation is releasing private information about your clients.