Vitalik Buterin, co-founder of Ethereum said:
There are some good ideas, there are a lot of very bad ideas, and there are a lot of very, very bad ideas, and quite a few scams as well
I agree. The are also some tokens or coins that are given freely as airdrops that are just scam or $hittoken on eth platform and are just being dumped on the market for the benefit of the devs to gain btc.
Some tokens and coins do have interesting use case. Do check always their whitepaper.