Personally , I don't think there should be an ICO without whitepaper. The whitepaper bridges the gap between an investor and a company. Can we say a ICO without a whitepaper is a scam? Or what can you say about an ICO without whitepaper
Generally with all legit projects they produce a whitepaper, but not ALL which don't have a whitepaper at the time are necessarily scams- some release their whitepaper after their website etc. but it should always be published at some point! The seeoner the better or it begins to affect confidence.