Legit or Scam

How should i know if the apps or links are legit or scam???At first when you play the games apps you really enjoy it.Coz you thought you can earn money like me..I download a lots of games,focus on it at first you will enjoy it.But as long as time pass the feeling is changing.You will get mad and delete the apps...But honestly i'm not investing money in links like trading bitcoins...I'm just looking for a free links and apps..So when you found it the apps or links are Scam you'll just say it's okay..I waste time but no money involve....thanks for reading guys..takecare