The word "scam" is ill-defined and thrown around far too easily when describing crypto-related ventures. I think the term needs to be backed up with something more than pointing to "this is imaginary wealth you're investing in".

ICO are essentially startups. They play with the hype generated by being first in (viz. Apple products or kickstarter) and thus allow those to promise something in the future while allowing speculation to almost guarantee wealth in the short term.