How to tell if an investment is real or not?

[Joe LaGreca]

I got an email from Alexx Varga the other day, inviting me to invest in his company, NextGen Housing.  

"We've got a great opportunity for you where you can lend a minimum of

$10,000 at 15% interest and get your return in six months."

http://www.nextgenhousing.com/

He is local to me in San Diego, but I'm not sure how to tell if it is a sound investment opportunity? The ROI sounds quite good, but the website is only 1.5 years old and the more I look into it, the more I question things.

I'm just curious how you all vet your investment opportunities?