Using Adwords
This is what they don't tell you.
A lot of those screen shots show you the money they brought in. They never tell you how much they spent to earn that income. They may make $600 a day but if they are using adwords to generate traffic then they likely spent several hundred a day as well. They always show you the gross, not the net. This doesn't mean that they aren't making a profit - they are or they wouldn't continue day after day - but that their profit is a lot less than they lead you to believe. This is done in order to make you believe that the product they are selling will help you generate profits of $600 a day. If they were completely honest they would admit that it might generate SALES of $600 a day - not PROFITS.
Using free traffic
This is what they don't tell you.
This is the best way for a beginner to start out. Build a blog on a particular niche(topic), create good quality content for it, have Google index and rank your page high for your keyword (topic) and sit back as Google sends hordes of visitors to your site. Finally, count your money from all the Adsense clicks. Right? Well almost.
This is the procedure but they don't tell you that to make serious money at this you will need to create hundreds or thousands of blogs. Yes, you heard right. Your main blogs will be decent pages addressing the needs of your visitors and suitable for marketing products. The majority of the blogs however, will be set up to simply generate Adsense clicks. The articles will be unique but crappy and visitors that end up on these blogs will quickly leave - hopefully by clicking an ad that will take them to where they were trying to go in the first place. This is called spam blogging and as unethical as it seems, it is how you make a lot of money with Adsense. No one talks about this aspect of making adsense profits. No one wants to admit that they use this tactic and yet this is the only way to generate a lot of money with Adsense with out spending money to get traffic.
This is also the system I recommend to all beginners. It's the cheapest way to start earning cash, it will teach you all the main aspects of Internet marketing and you can start immediately. However, you will have to decide if ethics or making money is your top priority first.