The are many ways to see a company for what it is. I will address some of the easiest ways.
1) way is to check with the better business bureau (bbb.org).
2) Another is to perform an asset search and see if the company has real financial backing or just cardboard behind the front door. Generally, the larger the companies provable assets the more comfortable you should feel in working with the company. In particular, if they are NYSE listed, then they are subject to much more rigorous government scrutiny.
3) Age of company- In contrast to publicly traded companies, the closest companies without real assets are often never subject to any scrutiny because they are in and out of business before too long (typically a few years).
4) Whois search will often give you a clue as to how credible a company might be. For example: take a company like stiforp.com If they are not hiding their contact info you can take their address and use Google maps to see how legitimate or big their physical address might be. I could find no record of any assets for this company. Certainly doesn't look like a big or credible company to me.
5) Don't buy into any company that promotes pre-launch hype & or no effort needed (this is equivalent of the company holding a large sign that says scam).
6) Any company that promises $1,000's with in days or no effort required, just turn and run.
7) Finally, never trust online reviews, they are almost always written by members of the company you are trying to find out about (with exceptions like consumer reports).

You may think, it's only X to join or .... but trust me doing your homework upfront will save you a ton of heartache after the fact.

Wishing you Success

Ray Van
http://www.FountainOfYouth411.com