A large number of them are scams. When I invest larger amounts of money, I am less likely to get it back.
I recommend investing small amounts in many different places.
The only place that ever paid me back an investment over $50.00 was sainv.com. and that is why I list them in my signature.
If they promise returns that are to good to be true, then they are a scam.
I have heard from other people that if they use very common templates for their websites, that is a bad sign. Also, some sites list their inverstors, payouts, investments, and so on. Sometimes if you look at them, the math does not add up.
There are a fiew good once out there, but they are more conservative in their promises of a profit.