Not to mention that there are ICOs who were run by scammers. Too good if it happens that the truth is revealed in an early stage. But yes, I agree a working product is a good indicator for its success.
I honestly don't think they are scamming people, I mean there was the dude that took everyone money and ran with it and left the website with "penis" written on it to troll the investors. That dude definitely did scam everyone and just recently we have seen that Pearl owner has printed a lot more pearls for himself and sold all of it causing the price to plummet and than ran with all the bitcoin he made from the sale. There are scam stories like that all the time but they are probably just 10% of all ICO stories. Rest of it, the 90% is actually teams that can't manage to run a proper business and actually succeed on being the ICO they promised to be. They either try and fail or they are too lazy to actually do it. All of them fail at what they suppose to do not because they are "bad" people but because they suck at what they do.
The viability of altcoins depends on the performance of the project team, and the usefulness and importance of the project itself.
But many people are not bothering about these but rushing to start a new ICO just to loot innocent people's money. There are two category of failing in ICOs : failure due to improper management and intentional scams. Improper management include the factors you have mentioned and the other category is just about what most people here are referring.