Just ask for a test drive and use the EA with your demo account. If the results are positive, then you can consider buying the same. Make sure that the seller is friendly and available when need arises. As far as I know there is no code to check whether the EA is profitable or not. Only a test on the real market can confirm the same.
i think the link is from a blog amd you put the same blog in your signature that mean that's your blog so have you tried the EA i nurse serious intentions of becoming one soon and probably writing an EA as soon as i finish my training