Some can definitely be a scam, I went over this a bit in one of my latest blogs. Paydirt is mores meant for beginners to guarantee they have success and learn proper panning techniques or for people who can't get out to gold bearing spots, say people who live in Florida, for example. There's no gold in that state! Or people who have disabilities which prevent them from gathering their own pay dirt.
I definitely won't be buying more. I wanted a small amount of gold just to do my testing with on the 3dp sluice so I can gauge how much gold I'm losing before I go and shove it in a creek and find it out the hard way.
I live in Nunavut and I know there's gold here, but because it's Inuit land I don't think it would be ethical for me to take their gold.
RE: Digging for gold