Who checks the sellers
Every seller must name a home parish, and it is shown on their listings. The diocese decides who may sell: anyone with a home parish, people known to their parish, or only people on a parish register. A seller can also be verified by their parish priest or by the diocese, and then shows a badge. Some kinds of listing can only be published by a verified seller.
Someone reads every report
The diocese appoints marketplace moderators. They cannot read every listing, but a person reads every report. A listing reported by several people is taken down until someone looks at it.
Featured listings
Some dioceses feature listings for a fee the diocese sets and collects itself. The seller pays the diocese directly. EcclesiaOne takes no part of it.
You and the seller arrange payment
Buyers and sellers arrange payment between themselves, usually at pickup. EcclesiaOne and the diocese do not hold or handle the money, and cannot get it back for you.
How disputes are decided
Payment is between buyer and seller, so EcclesiaOne cannot refund you. If a seller breaks the rules, report the listing: the diocese marketplace moderators can take it down or remove the seller.
A seller who breaks the rules can lose their verification or be removed from the marketplace.