A scam is a situation where we are deceived.
there is a characteristic scam cryptocurrency that can be seen at the beginning, such as
-No whitepaper or no clear whitepaper
-No web or low quality web
-No vision mission or short term target and long term target
-No roadmap
-the dev profile is hidden
-Passive community with the dev team
-etc

but there are also those who can not see until the end, even from the beginning it looked promising but finally we got a scam too.
this type is very difficult to detect a scam or not.