None of these coins are truly backed by gold, the truth is the creators on most of this could redeem all of the gold and it's as easy as that. They fool people into thinking there is a physical gold to float the price of the coin but the truth is if there is any it is theirs. I doubt any of these projects has people redeeming any physical gold who isn't an alt of the creator.
Some of them claim that they can provide some guarantees, for example, an independent audit made by a few different third-party companies 2-3 time a year. This is just one of the examples. Is it even possible to provide investors with such guarantees? Or you can never trust such projects in your opinion?