How to know if a new altcoin is a promising one or only a scam?

[Willitivity]

It involves some deep research into the project and looking up on the teams involved.
Also, check the website, read the whitepaper, make contact to the team members via their social platforms.
Most importantly, projects with working products are more real than projects that give fantasy promises.

[Zerosk]

First identify if the Token is a Security or Utility. If it's a Security, then there are higher chances that the ICO will be scam. Read the Whitepaper to see if they can deliver with their Blockchain application (if it will be within the Blockchain), check the ICO team's background and Founder's and check if there is a legal entity behind the ICO

[FrankNoland]

There's a lot of new coin or token coming almost everyday and i experienced that some of them are having no value until now. So I'm asking now for me to determine next time the good one so that my exerted efforts to join them will not be wasted. Thank you. Hehehe

The answer to your question is quite easy: read, research and investigate. Don't invest in projects you don't know or barely understand. New coins are launching everyday/week now, and at times it might be difficult to conclude whether its worth investing in or is probably just another scam. However, reading, researching and investigating might eliminate all these challenges since you will be able to conclude on your own whether the project is invest worthy or not.

[Allan Ramanda]

before choosing altcoin, you should look at their threads, learn how their ico runs, and what you need to see is their white paper, there you can conclude your own decision about what coin they market

[coastbank]

I suppose its pretty much luck. I try to read experienced investor/users around here. Then I read devs linkedin profiles. Investigation is enough for it to understand if its scam or not. Whitepaper is also good place to look.

[Blake_Last]

It's really hard to say. You see, some scam ICOs nowadays hire writers and developers to make their project appear legit. They even make their white paper appealing and convincing that makes it hard to know if they are promoting a fake project or not.

So usually the best thing one can do when it comes to this, or when it comes to checking if an ICO is a scam or not, is not to focus mainly on the white paper, but focus more on their team, especially the founders and developers. If the project is transparent, they will not hide any information about their management to anyone interested to know it.

[Avity]

Joining Airdrops is a simple way to obtain new altcoins with an investment of time.  However with an investment of your own capital, I would make sure that you believe in the project beyond a doubt, investigate the team members behind the idea, see how much capital they are already working with, therefore valuing the token or coin itself already.