I've been a Prime member for years, and I order stuff very often so the free shipping definitely is worth the membership fee.

I always use the "Amazon Prime" filter when I search, and I've never had any issues with those items. Sellers have to share a little more profit with Amazon to be listed as Prime, but I think that's enough of a bar to eliminate the fraudsters.

The only times I've had problems were with non-Prime sellers, but luckily those were just long-delays rather than outright fraud.