With these websites, the only way to find out is to try them - at your own risk...not that I suggest you do that. Sometimes, people who say that these sights are great are their own marketers - creating buzz.
To assume loans, you have to qualify for them, and, you have to really know that the owners are who they say they are, and the paperwork is not done to get your money and run.
So, you are right to be careful.
Hope this helps,
Beachfront Realty, Inc.