MQL doesn't like critical reviewers like me...
My proven rules established over years to choose an EA (95% of vendors here does not even come close):
1) Vendor shows a decent sized (3-5k EUR balance) live account on a reputable ECN broker, not a CENT account, with at least 3 months full history to be analyzed on m*fxbook
2) Vendor cares about showing a proven EA first, before aggressively upping the price
3) Vendor is able to explain how the EA controls the risk (prevent big floating DD, prevent big losses, news filter, trading hour filter, which market situations are good which are not good or the EA, ect.)
4) Vendor is uploading the full 99% backtest we can download as .zip, done using Tickdata Suite, where we can see all settings. Max spread or floating spread from which tickdata provider is explained.