I think you should be the one to judge whether an altcoin is ok or not because it is your investment some people may help you judge coin and give wrong judgement about it. First of all you can check the tokenomics, whitepaper, market capacity, etc. this are some of the basics but you can also take consider how big the community is or what kind of promotion strategies they are using.
Actually it is not easy to choose new projects for investment, it takes good analytical skills, in order to be able to assess whether the project is
potential or not. My advice for beginners is to invest in the top 10 altcoins that do have a high demand, If we want to be safer, we can focus on
investing in Bitcoin. What you say is true who can judge altcoins good or not, only we ourselves, because the opinions of others can not be used
as a guarantee. Therefore, before choosing altcoins, always do your own research and analysis.