Well to start off they're Hundreds maybe even Thousands of Pay to click Scams!!!
I have a few that I know for a fact aren't scams. Each of these sites have paid me multiple times. Abslolutely Legitimate websites. They are great ways to earn a little extra money on your wallet. To maximize the amount that you get you should try to sign-up to more than one of these sites. Thank You and Enjoy Your Cash!!!
The first my favorite is- http://www.waoindia.com/register.php?r=david504
This site is absolutely amazing everythingyou want in a PTC site. Ten cents per ad and a great referral program. This site has paid me three times. Each of $199. All together that was the easiest $600 that I have ever earned.
The Second site is also Very Good- http://www.youdata.com/join/david504
Another Good PTC. I have earned over $2oo dollars with this site also. Also has a very good referral program. This site pays a little less than the above site,(5-10 cents per ad)but it is still very good.
The Third site is Extraordinary- http://www.neobux.com/?r=david504
On this site you start of pretty slow, (only 1 cent per ad) but this has the best ever referral site. From my referrals only i made $25 dollars in about five days. That ads up over time ads up to a lot. Just a way to put extra money in your pocket for doing basically "nothing"