https://bitcoinmagazine.com/article...s-monero-developer-riccardo-spagni-1458743546 “The majority are outright scams. There's no mincing words with this, and I think it's absolutely disgusting. From obvious premined or instamined scams, to the more subtle mining scams that attempt to hide the premine from block explorers, there are a lot of scams meant to outrightly enrich the creators. Identifying scams is made doubly difficult because of the existence of professional, highly motivated groups that are behind them, who often co-opt innocent developers who think they're genuinely building something unique.”
Well what exactly do you mean by useful. Even scamcoins are useful for some, it's possible to make a considerable amount of money just following pump and dumps intelligently. Useful coins to me are ones that highlights an issue, fix a problem, or bring something new to cryptocurrency all together. I think DASH with Darksend, Ether with simplicity, Decred with the focus on decentralization and community support, and others like these.
Well, if you PoW/PoS mine or design altcoins in the goal of trading them on Bleutrade as soon as your money is made, in other words ''somebody else, please, grab that crap from me before it worths nothing'', then you see altcoins from the same eyes as me.
Siacoin will buy you redundant, encrypted and decentralized storage space in the cloud. That's useful I think. There are other useful coins too, which I'm sure fluffypony know about hence his statement about the "majority" which I agree with.