Yes you are so right, there are many scams and one has to do their due diligence before joining a program. Even then sometimes you may get scammed so just be very cautious when joining any programs online. Many times you have friends in programs and they can help you decide if the program is worth joining or not.
I do know there are many sites where you can write articles and make money from them. I have done this for the past five years or so off and on and it is a legitimate business. You do not have to put any money up front. There are also many legitimate companies that are hiring people and their links are usually at the bottom of the website for hiring or employment, if you are interested. Just a little fyi for those who might be in the market for an online job.
Of course there are your survey sites who pay you to give them your opinion on many different subjects and products. I have made money from these also for the past 10 years or so but never made enough to make a living at, just a little extra for gas or other expenses.